“I Don’t Know” in Japanese – Learn the different ways

In this lesson, we will focus on how to say “I don’t know” in Japanese and related phrases in everyday conversations.

Getting familiar with the phrase “I don’t know” is a must-have knowledge for entry-level to intermediate-level language learners. Let’s get to it!

How to Say “I Don’t Know” in Japanese

The “I don’t know” expressions are practical and functional in various situations, whether you are a traveler or a worker in Japan.

You can communicate with the phrases below with confidence:

にほんごがよくわかりません (Nihongo ga yoku wakarimasen | 日本語がよくわかりません)

I don’t understand Japanese very well.

すみません、あなたのなまえをまだしりません (Sumimasen, anata no namae wo mada shirimasen | すみません、あなたの名前をまだ知りません)

Sorry, I don’t know your name yet.

Let’s get started to brush up on your Japanese knowledge!

The Basic Way to Express “I Don’t Know” in Japanese

The topic in this course today is 知らない (shiranai | しらない ) and 分からない (wakaranai | わからない) in Japanese.

Both are the negative forms of the verbs 知る (shiru | しる) and わかる (wakaru | 分かる), and these are the two main ways to say “I don’t know” in Japanese.

Simply put, 知る (shiru) means to know, and 分かる (wakaru) means to be understandable in Japanese.

They work almost identically to English “I don’t know” and “I don’t understand” but require a deeper understanding of words and contexts to use correctly.

First, let’s take a look at the basic expressions.

Casual form for “I don’t know” in Japanese

• しらない (Shiranai | 知らない | I don’t know)
• わからない (Wakaranai | わからない | I don’t know, I don’t understand)

Polite form for “I don’t know” in Japanese

• しりません (Sirimasen | 知りません | I don’t know)
• わかりません (Wakarimasen | わかりません | I don’t know, I don’t understand)

Colloquial expression for “I don’t know” in Japanese

• しらないです (Shiranai desu | 知らないです | I don’t know)
• わからないです (Wakaranai desu | わからないです | I don’t know, I don’t understand)
• しらん (Shiran | 知らん | I don’t know)
• わからん (Wakaran | わからん | I don’t know, I don’t understand)

Grammar Note:

It might sound familiar to a beginner learner, though the following four phrases are not grammatically correct.

Still, some Japanese use しらないです (shiranai desu) and わからないです (wakaranai desu) in casual speaking, so be aware of it. しりません (shirimasen) and わかりません (wakarimasen) are the expressions without grammatical errors you should remember.

• しらないです (Shiranai desu | 知らないです | I don’t know)
• わからないです (Wakaranai desu | わからないです | I don’t know, I don’t understand)
• しっていない (Shitteinai | 知っていない) *literally, it would be translated to “I’m not knowing”
• しっていません (Shitteimasen | 知っていません) *literally, it would be translated to “I’m not knowing”

“I Don’t Know” in Japanese using different kanji

The Japanese phrases しらない (shiranai) and わからない (wakaranai) are both easy to remember, but the meaning of each phrase can change depending on the situation and context. So, you should learn the meaning and grammar points to use them comfortably in a conversation.

To start, let’s take a look at its Chinese character.

しらない (shiranai) has only one かんじ (Kanji | 漢字 | Chinese character). On the other hand, わからない (wakaranai) has three, and they convey a slight difference in meanings.

See the main difference between words and how to use them in the example sentences below.

 知

The Chinese character “知” implies knowledge, understanding, and feeling with the heart in Japanese. The verb 知る means “to know” and “to understand” in Japanese. Besides, 知らない (shiranai) and 知りません (shirimasen) are technically replaceable for “I don’t know” phrases in English.

Affirmative form

• しる (Shiru | 知る)
• しります (Shirimasu | 知ります)

Negative form

• しらない (Shiranai | 知らない)
• しりません (Shirimasen | 知りません)

Typically it’s used in a situation when:

• You don’t have the knowledge/memory/skill of something
• The facts are not clear to you
• You are unable to perceive something
• You haven’t experienced or heard/seen/smelled/tasted/touched something
• You don’t want to take responsibility for something
• You don’t acknowledge the state/content/value

Examples:

ぼくはなにもしらない (Boku wa nani mo shiranai | 僕は何も知らない)

I don’t know anything, or I know nothing

しらないし、かんがえたくもない (Shiranai shi, kangae taku mo nai | 知らないし、考えたくもない)

I don’t know, and I don’t even want to think about it

よのなかのくろうをしりません (Yo no naka no kurou wo shirimasen | 世の中の苦労を知りません)

I don’t know the hardships in the world

分, 判, and 解

In Japan, わからない (wakaranai) and わかりません (wakarimasen) are often written in ひらがな (Hiragana), but it also has three different ways to write using Chinese characters, “分,” “判,” and “解.”

Essentially, the meaning of a sentence can alter depending on the Chinese character you use.

If you aren’t sure about which word you should choose or which word fits the context better, you can always write it in Hiragana. Still, let’s get a clue about each word’s difference.

Affirmative form

• わかる (Wakaru | 分かる、判る、解る)
• わからない (Wakaranai | 分からない、判らない、解らない)

Negative form

• わかります (Wakarimasu | 分かります、判ります、解ります)
• わかりません (Wakarimasen | 分かりません、判りません、解りません)

分

The Chinese character “分” implies understanding, recognition, and distinction. It’s a じょうようかんじ (Jouyou Kanji | 常用漢字 | Regular-Use Chinese Characters) unlike “判” and “解.”

分からない is the most commonly written word for “I don’t know,” “I don’t understand,” and “I’m not aware of it” in Japanese. It technically covers the meaning of “判” and “解.”

Affirmative form

• わかる (Wakaru | 分かる)
• わかります (Wakarimasu | 分かります)

Negative form

• わからない (Wakaranai | 分からない)
• わかりません (Wakarimasen | 分かりません)

Typically it’s used in a situation when:

• You aren’t aware of something
• Something isn’t understandable
• You don’t understand something or the situation the other person is in
• You can’t distinguish one thing from another

Examples:

まったくわかりません (Mattaku wakarimasen | まったく分かりません)

I’m completely lost. / I don’t get it at all.

かれのきもちがわからない (Kare no kimochi ga wakaranai | 彼の気持ちが分からない)

I don’t know how he feels. / I don’t understand his feelings.

きょうのてんきはよくわからない (Kyou no tenki wa yoku wakaranai | 今日の天気はよく分からない)

The weather seems strange today / I have no clue about the weather today.

判

The Chinese character “判” implies recognition, realization, and judgment in Japanese. The state of 判る (wakaru) and 判らない (wakaranai) don’t require logical thinking, but it’s connected to well-known facts, visual impressions, and sensorial conclusions.

The word 判らない for wakaranai is rarely used in comparison to the “分からない” and “解らない” but literally conveys the meaning of unknown or unrecognizable in English.

Affirmative form

• わかる (Wakaru | 判る)
• わかります (Wakarimasu | 判ります)

Negative form

• わからない (Wakaranai | 判らない)
• わかりません (Wakarimasen | 判りません)

Typically it’s used in a situation when:

• The facts aren’t clear
• You can’t reach a conclusion about something
• Something becomes known to others

Examples:

まだあしたのよていがわかりません (Mada ashita no yotei ga wakarimasen | まだ明日の予定が判りません)

I don’t know the schedule for tomorrow yet.

はんにんはまだわからないようだ (Hannin wa mada wakaranai you da | 犯人はまだ判らないようだ)

It seems they can’t get the picture of the culprit yet. / The culprit is still unknown.

しかくてきにはわからない (Shikakuteki ni wa wakaranai | 視覚的には判らない)

It’s visually indistinguishable. / I don’t see it visually.

解

The Chinese character “解” implies comprehension, realization, and explication in Japanese. It’s the appropriate word if you have a problem understanding an academic issue or a fact-related matter which requires a thinking process.

Affirmative form

• わかる (Wakaru | 解る)
• わかります (Wakarimasu | 解ります)

Negative form

• わからない (Wakaranai | 解らない)
• わかりません (Wakarimasen | 解りません)

Typically it’s used in a situation when:

• You have no clue about the meaning, contexts, value, and other things
• You aren’t familiar with something
• You don’t get it even after thinking

Examples:

ぜんぜんわからない (Zenzen wakaranai | 全然解らない)

I don’t get it at all. / I have no idea.

このもんだいのこたえがわかりません (Kono mondai no kotae ga wakarimasen | この問題の答えが解りません)

I don’t know the answer to this question.

いっているいみがわからない (Itteiru imi ga wakaranai | 言っている意味が解らない)

I don’t understand what you mean. / I don’t get what they mean.

Tip to Learn I don’t know in Japanese: Verbs and Adjectives

Some Japanese learners might assume しらない (shiranai) and わからない (wakaranai) as adjectives instead of verbs since both words end with い (I), like an i-adjective.

Examples of i-adjective:

• かわいい (Kawaii | 可愛い | cute)
• おいしい (Oishii | 美味しい | tasty)

However, 知る (shiru)/知らない (shiranai) and わかる (wakaru)/わからない (wakaranai) are technically verbs and not adjectives.

• verb: しる (Shiru | 知る | to know, to understand) → しらない (Shiranai | 知らない)
• verb: わかる (Wakaru | わかる | to know, to understand) → わからない (Wakaranai | 分からない、判らない、解らない)

Additionally, when a noun follows 知らない (shiranai) and わからない (wakaranai), they work like an adjective instead of a verb. It’s called the negative auxiliary verb in the Japanese grammar term. Some learners might be acquainted with the term ない (Nai) form verbs.

Examples:

しらないひとたち (Shiranai hito tachi | 知らない人たち |

strangers / unfamiliar people

わからないこと (Wakaranai koto | わからない事 |

the thing I don’t know / something you don’t understand

にほんごがわからないとき (Nihongo ga wakaranai toki | 日本語がわからない時 |

When I don’t understand Japanese. / When you don’t understand Japanese.

しらないたんごははつおんのしかたがわからない (Shiranai tango wa hatsuon no shikata ga wakaranai | 知らない単語は発音の仕方がわからない |

I don’t know how to pronounce a word I haven’t learned.

しらなかったことがわかるのはうれしい (Shiranakatta koto ga wakaru no wa ureshii | 知らなかった事がわかるのは嬉しい |

I’m happy to learn things I didn’t know before.

Note:

Don’t forget to pay attention to hidden subjects and objects together with verbs in sample Japanese sentences.

In casual speech, Japanese people often omit them, so you should pay close attention to the whole context to grasp the meaning completely.

How to Express “I Don’t Know” in Past Tense in Japanese

In this chapter, we will be presenting example sentences in the past tense.

Examples with the verb 知る (shiru)/知らない (shiranai)

このニュースをしっていましたか？ (Kono nyuusu wo shitteimashita ka? | このニュースを知っていましたか？)

Did you know this news?

そのニュースをしりませんでした (Sono nyuusu wo shirimasen deshita | そのニュースを知りませんでした)

I didn’t know the news, I haven’t heard the news.

かれがなくなっていたなんてしらなかった (Kare ga nakunatteita nan te shiranakatta | 彼が亡くなっていたなんて知らなかった)

I didn’t know he passed away.

いままでしらなかったけど、このレストランはなかなかいいね (Ima made shiranakatta kedo, kono resutoran wa nakanaka ii ne | 今まで知らなかったけど、このレストランはなかなかいいね)

I didn’t know this until now, but this restaurant is pretty good.

Examples with the verb 分かる (wakaru)/分からない (wakaranai)

いちねんまえはにほんごがわからなかった (Ichinen mae wa nihongo ga wakaranakatta | 一年前は日本語がわからなかった)

I didn’t understand Japanese a year ago.

こどものころはおかねのかちがよくわかっていなかった (Kodomo no koro wa o kane no kachi ga yoku wakatteinakatta | 子供の頃はお金の価値がよくわかっていなかった)

When I was a kid, I didn’t understand the value of money well.

どちらがおいしいかわからなかった (Dochira ga oishii ka wakaranakatta | どちらが美味しいがわからなかった)

I didn’t understand which one was tastier.

いっしゅん、なにをいわれたかわかりませんでした (Isshun, nani wo iwareta ka wakarimasen deshita | 一瞬、何を言われたかわかりませんでした)

For a moment, I didn’t understand what you told me. / For a moment, I didn’t understand what they said.

Friendly Way to Express “I Don’t Know” in Japanese

Essentially, しらない (shiranai) is the most casual way to express “I don’t know” in Japanese and a suitable expression among friends and families.

Yet, it could be a rather blunt expression on some occasions.

If you prefer a little friendlier tone, you can add な (Na) / よ (Yo) / わ (Wa) and a similar phrase at the end and say しらないな (shiranai na) or わからないわ (wakaranai wa).

Probably, it’s the same reason that some native Japanese speakers prefer grammatically wrong expressions such as しらないです(shiranai desu) and わからないです (wakaranai desu) over しりません (shirimasen) and わかりません (wakarimasen) when they talk to others.

Examples:

しらないよ、きいたことがない (Shiranai yo, kiita koto ga nai| 知らないよ、聞いたことがない)

I don’t know, never heard of it.

そんなひとはしらないな (Sonna hito wa shiranai na | そんな人は知らないな)

I don’t know anyone like that. *a slightly manly expression

きっとあなたはしらないわ (Kitto anata wa shiranai wa | きっとあなたは知らないわ)

I’m sure you don’t know. *a feminine expression

いみがわからないよ (Imi ga wakaranai yo | 意味がわからないよ)

I don’t understand you.

かれがくるがどうかはわからないな (Kare ga kurukadouka wa wakaranai na | 彼が来るかどうかはわからないな)

I don’t know if he will come. *a slightly manly expression

わからないわ、あとできいてみることにしましょう (Wakaranai wa, ato de kiitemiru koto ni shimashou | わからないわ、後で聞いてみることにしましょう)

I don’t know, let’s ask later. *a feminine expression

In addition, you can show the other person a light or carefree attitude by adding かな (Kana | I wonder) / かもしれない (Kamoshirenai | maybe, perhaps) / じゃない (Janai | maybe, most likely)

It’s also a common expression when you want to give someone an indefinite reply.

Examples:

テストがあるなんてしらなかったかも (Tesuto ga aru nan te shiranakatta kamo | テストがあるなんて知らなかったかも)

I didn’t know there was a test.

きょうじゅうにはわからないかもしれません (Kyoujuu ni wa wakaranai kamo shiremasen | 今日中にはわからないかもしれません)

I may not know by the end of the day.

かのじょはしらなかったんじゃないかな (Kanojo wa shiranakattan janai kana | 彼女は知らなかったんじゃないかな)

Maybe she didn’t know.

How to Say “I Don’t Know Politely in Japanese

The following polite forms are the standard for “I don’t know” in Japanese. You can use these phrases with an older person, teacher, colleague, or stranger.

These are called ていねいご (Teinei Go | 丁寧語 | polite language) or ですますちょう (Desu-Masu Chou | ですます調 | desu-masu style) in Japanese.

• しっています (Shitteimasu | 知っています | I know, I have a clue)
• わかります (Wakarimasu | 分かります、判ります、解ります | I know, I understand)
• しりません (Shirimasen | 知りません | I don’t know, I have no clue)
• わかりません (Wakarimasen | 分かりません、判りません、解りません | I don’t know, I don’t understand)

Five Types of Japanese Honorifics

The phrases above are not for every formal situation. Native Japanese speakers use そんけいご (Sonkeigo | 尊敬語) and けんじょうご (Kenjougo | 謙譲語) in formal speaking and writing among the five types of Japanese honorifics.

If you are talking to someone at work in a formal situation, use the following expressions instead. They are also commonly used in the customer service field, so when you ask someone about something as a customer, you might get these extremely polite replies.

These are the five different types of honorifics in Japanese, referred to as けいご (Keigo | 敬語 ).

• そんけいご (Sonkeigo | 尊敬語 | respectful languages)
• けんじょうご (Kenjougo | 謙譲語 | humble languages)
• ていちょうご (Teichougo | 丁重語 | courteous languages)
• ていねいご (Teineigo | 丁寧語 | polite languages)
• びかご (Bikago | 美化語 | elegant and refined languages)

Essentially, it’s a complex topic even for a native Japanese speaker, but we will show you some typical Japanese phrases and the literal translation of English here.

しらない (Shiranai | 知らない) becomes:

ぞんじる (Zonjiru | 存じる) is the appropriate expression when referring to the knowledge of an item, situation, or schedule.

• ぞんじない (Zonjinai | 存じない)
• ぞんじません (Zonji masen | 存じません)
• ぞんじておりません (Zonjite orimasen | 存じておりません)

しらない (Shiranai | 知らない) and わからない (Wakaranai | 分からない) become:

ぞんじあげる (Zonji ageru | 存じ上げる) is used when the object of knowledge is related to people.

• ぞんじあげない (Zonji age nai | 存じ上げない)
• ぞんじあげません (Zonji age masen | 存じ上げません)
• ぞんじあげておりません (Zonji agete orimasen | 存じ上げておりません)

わかりかねる (Wakarikaneru | 分かり兼ねる) is the way to address things you do not know politely. In addition, they sometimes convey the meaning of hesitation to make a decision, impossibility, and difficulty. Therefore, the other party might get offended if someone misuses them.

• わかりかねる (Wakarikaneru | 分かり兼ねる、わかりかねる)
• わかりかねます (Wakarikanemasu | 分かり兼ねます、わかりかねます)

Examples:

たいへんきょうしゅくですが、そのけんにかんしてはぞんじません (Taihen kyoushuku desu ga, sono ken ni kanshite wa zonji masen | 大変恐縮ですが、その件に関しては存じません)

I’m very sorry, but I don’t know about that matter.

そのかたをぞんじあげません (Sono kata wo zonjiagemasen | その方を存じ上げません、その方を存じあげません)

I don’t know the person.

おこたえいたしかねます (Okotaeitashikanemasu | お答え致し兼ねます、お答えいたしかねます)

I can’t answer your question.

へいしゃにはわかりかねます (Heisha ni wa wakarikanemasu | 弊社には分かり兼ねます、弊社にはわかりかねます)

Our company doesn’t have the knowledge.

てんこうによりますので、こちらではわかりかねます (Tenkou ni yorimasu no de, kochira de wa wakarikanemasu | 天候によりますので、こちらではわかりかねます)

It depends on the weather, so I can’t give you the exact answer.

Idioms and Other Ways to Say “I Don’t Know” in Japanese

Japanese phrases similar to “I don’t know what to do:”

• どうしよう (Doushiyou | どうしよう)
• はてさて (Hate sate | はてさて)
• オロオロ (Oro oro | おろおろ)

Japanese phrases similar to “I have no idea”/”I don’t have the slightest idea:”

• かいもくけんとうもつかない (Kaimoku kentou mo tsukanai | 皆目見当もつかない)
• いみふめい (Imi fumei | 意味不明)
• りかいふのう (Rikai funou | 理解不能)
• チンプンカンプン (Chin pun kan pun | ちんぷんかんぷん)

Japanese phrases similar to “I have no recollection”/”I don’t remember:”

• みにおぼえがない (Mi ni oboe ga nai | 身に覚えがない)
• おもいあたるふしがない (Omoi ataru fushi ga nai | 思い当たる節がない)
• こころあたりがない (Kokoro atari ga nai | 心当たりがない)
• きおくがおぼろげ (Kioku ga oboroge | 記憶が朧)

Japanese phrases similar to “I don’t get it:”

• りかいにくるしむ (Rikai ni kurushimu | 理解に苦しむ)
• げせない (Gesenai | 解せない)
• ふにおちない (Fu ni ochinai | 腑に落ちない)
• モヤモヤする (Moya moya suru | もやもやする)

Gestures used to express “I don’t know” in Japan

As you might know, shrugging shoulders or stretching your arms with palms facing up is one of the typical gestures with the meaning of “I don’t know” in many Western countries.

Many Japanese people understand them, but they don’t use them on their own.

Instead, Japanese people use different types of body language. For example, tilting the head, touching the chin with a hand, crossing their arm in front of the chest and making an X sign, and waving a palm-closed hand in front of the face is a sign that means “I don’t know” in Japan.

It’s common to make a frowning face and not say a word while performing these gestures in Japan. If you don’t understand what their gestures mean, don’t hesitate to ask them directly. Most likely, they will reply to you in a friendly manner.

Summary

Once you get the idea of the main difference between the words しらない (shiranai) and わからない (wakaranai), it’s easy to say “I don’t know” in Japanese.

If you haven’t yet, you might also want to learn how to say “I know” in Japanese.