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How to Say “I don’t know” in Japanese

How to Say “I don’t know” in Japanese

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One useful trick for language-learning is to make a point of figuring out how to ask for help early on.

If you’re visiting a traditional Japanese inn and the front desk staff just asked you a question, your trip is going to go a lot more smoothly if you can clue them in to the fact that you don’t have a clue what they said.

In that vein, the phrase “I don’t know” or “I don’t understand” can be a life-saver.


How do you say “I don’t know” in Japanese?

The two standard ways to say ‘I don’t know’ in Japanese are 「知りません。」 (shirimasen) and 「分かりません。」 (wakarimasen).” There are two main ways to say you know or understand something in Japanese. The first of these is 知る (shiru), a verb meaning “to know,” and the second is 分かる (wakaru), closer in meaning to “to understand.”

Both are godan verbs ending in -ru, which means the negative is formed in the same way for both. 知る becomes 知らない (shiranai) or, more formally, 知りません (shirimasen), while 分かる becomes 分からない (wakaranai) or 分かりません (wakarimasen).

Another option is the old-fashioned 心得ません (kokoroemasen).

There are a few other verbs which mean “to know,” but they are typically reserved for specific situations or aren’t typically used in a way that means “I don’t know.”

In most cases, you should use 知りません or 分かりません instead.


知る and 分かる: two slightly different verbs for “to know”

The most common Japanese words that mean “to know” are 知る (shiru) and 分かる (wakaru).

The main difference between the two is that 知る means know in the sense of “to be aware of” and 分かるimplies that you understand something as the result of research, study or expertise.

If someone were to say 「あ、知っています!」 you might think of this as meaning “Ah, I’ve heard of that!”

分かる, on the other hand, is typically reserved for intellectual matters, so 「分かっています!」 might be more like “I’ve got it!”

Both these verbs are “godan” verbs, which means to get the base form you simply remove the る from the end.

Because the based form is what’s used to form the negative, knowing this is important if you’re trying to say “I don’t know.”


「この質問を知っていますか?」 “Do you know this problem?”


“Do you understand this problem?”


These two examples make clear the subtle difference between the two words.

Imagine these “problems” are math problems on a homework assignment.

In the first example, the question could be rephrased as “do you know of this problem?” Basically, the speaker is asking if the listener is aware of the specific problem.

In the second, the speaker is asking more along the lines of “do you know the solution to this problem?”


Saying “I don’t know” with 知りません (shirimasen)

In most contexts, the best way to say you don’t know something is to use the word 知りません.

This is the polite negative form of the verb 知る.

As already established, 知る means “to know,” a fact reinforced by its being written with the kanji 知, meaning “wisdom” or “knowledge.”

Again, this is “to know” in the generalized sense. It can also be used to refer to people.

If you’re speaking casually, you can say 知らない (shiranai).


「知らないよ、あの本!」“I don’t know that book!”


“Nobody knew him.”


Saying “I don’t understand” with 分かりません (wakarimasen)

Unlike 知りません, 分かりません should only be used when you literally don’t understand how to do or say something.

This means it can be a good stand-in for “I don’t know” when someone is asking you questions about language, math, or another academic topic.

However, keep in mind that it does technically mean more like “I don’t understand.”

In a less formal setting, you can use 分からない (wakaranai) instead of 分かりません.



“Excuse me, how does Mahler’s fourth symphony start?”

“I don’t know anything about that!”


「エリカさん、”I don’t know”は日本語でどう言いますか?」「え?ごめん、分からない。」

“Erika, how do you say ‘I don’t know’ in Japanese?”

“Huh? Sorry, I don’t know.”

In these examples, 分かりません can be translated as “I don’t know.”


Using 心得ません (kokoroemasen) for “I don’t understand”

The verb 心得ません (kokoroemasen) is a third option that can be used in some cases to mean “I don’t know.”

The kanji in this word are 心 (kokoro), meaning “heart” or “mind,” and 得る (eru), meaning “to gain” or “to get.” Literally, then, this word means you “get [something] in your mind.”

Much like 分かる, 心得る carries a connotation of intellectually understanding something.

In fact, 心得る is essentially an old-fashioned synonym for 分かる.

心得る is an ichidan verb, so to make it negative you drop the る and add ない or ません.

This gives us a negative form of 心得ません (kokoroemasen) or 心得ない (kokoroenai).

You probably wouldn’t use this word to say you don’t know or don’t understand something.

However, in some contexts, like formal essay writing, it may be appropriate.


A note on subjects

It’s worth mentioning that none of the example sentences above include a specific subject.

Japanese is a high-context language, so it’s not usually necessary to include one.

Without any context,「知りません。」technically just tells you that someone doesn’t know something.

To explicitly include yourself, you would need to say「私は知りません。」or「私は分かりません。」

However, including the word for “I” actually just puts the focus on you.

That is, it sort of implies that while some people might know something, you certainly do not.

For that reason, it’s usually best to just say「知りません。」or「分かりません。」without any explicit subject. People will understand what you mean.


7 other ways to say “I don’t know” in Japanese

In Japanese, it is important to understand the subtext of every conversation. 

There are many omitted words and meanings when using Japanese language, so it can be difficult for a beginner to understand exactly what the speaker means.

It can be dangerous to nod along with things you do not fully understand, so make sure to tell the person you’re speaking to if there’s something you didn’t quite get!

Learning the phrase “I don’t know” is a must for beginners of Japanese! 

While wakarimasen (分かりません) and shirimasen (知りません) are the most common ways to say it, these are not the only phrases we can use.

Let’s look at some other ways you can say “I don’t know” in Japanese.


Wakannai (分かんない)

Wakannai is an informal slang version of wakaranai, which is the informal version of wakarimasen. 

As you can see, it is a doubly informal version of the original, so be sure to only use this around close friends or family.

The basic meaning of 分かんない is “I don’t understand”, which is the same as the more formal version 分かりません.

 The two phrases have a slight difference in tone and formality, however.

Because of this word’s informality, it is more akin to a casual “no idea” or “no clue”. 

Example: How to Use “Wakannai” in a Sentence

なぜ彼は怒っているのですか? 分かんない.

Naze kare wa okotte iru no desu ka? 


Why is he angry? 

No clue.


Shinnai (知んない)

Shinnai is the informal slang version of shiranai, which is the informal version of shirimasen. It is most often used within the Tokyo metropolitan area. 

It is also a doubly informal version of it’s original, so you should not use it in formal situations, or toward those older than you.

The meaning of shinnai is still “I don’t know (it)”, but a bit less formal. It is more similar to the phrases “Never heard of it” or “No clue what you’re talking about”. 

A bratty child may say it when asked a question about a subject they’re unfamiliar with, but this is a slightly rude thing to say unless it’s between close friends and family.

Let’s check an example of its usage.

Example: How to Use “Shinnai” in a Sentence


Eki no chikaku no resutoran o shitte imasu ka?


Do you know the restaurant by the station?

Never heard of it.


Shiranne (知らんね)

Another slang version of the original “shirimasen” (知りません) is shiranne (知らんね). This is a rather rude way of saying “I don’t know”, but it is common in many types of media. 

知らんね comes off as angry or irritated, and should be avoided in any formal situation.  It is sometimes used by lazy/bored people or characters as well, to indicate that they are very nonchalant. 

Because of the harsh tone this word carries, you may hear it in action movies, videogames, and anime.

Unless you have a good grasp on the Japanese language, it’s best to avoid this one in order to avoid offending people. 

Examples: How to Use “Shiranne” in a Sentence

こんなに簡単なことを知らないの?うるさい! 知らんねよ! 

Konna ni kantanna koto o shiranai no?

Urusai! Shiranne yo!

Don’t you understand something this simple?

Shut up! I don’t know! 


Zen zen shiranai (全然知らない)

“Zen zen shiranai” is a phrase which means “I don’t know it at all.” It’s usually used in instances where the listener has never heard of the subject at hand, or has no knowledge of it. 

“Zen zen” (全然) means “at all”. We add this in front of our word for “don’t know”, which can be the more formal “shirimasen”, or the casual “shiranai”. 

It is more commonly used with the informal version shiranai (知らない) as zenzen (全然) is a bit casual. 

This phrase is often used if a listener learns of a brand new thing that they had no prior knowledge of, and they are amazed. 

Example: How to use “Zen zen shiranai” in a sentence

彼が医者だったことを知っていますか?ええ?! 全然知らなかった!

Kare ga isha datta koto o shitte imasu ka?

Eeh?! Zen zen shiranakatta!

Do you know he used to be a doctor?

Eh?! I didn’t know that at all!


Zen zen wakaranai (全然らない)

“Zen zen wakaranai” is a phrase that means “I don’t understand it at all”. If someone doesn’t know or understand something, they may let out an exasperated 全然らない. 

This is commonly used by students who struggle with concepts at school. It uses the informal wakaranai (らない) because “zen zen” itself is a casual add-on, which means “at all”. 

This phrase should be used only with people you are close to, as it would be rude to use it at work when a superior is trying to teach you something. 

Example: How to use “Zen zen wakaranai” in a sentence


Kono mondai o kaiketsu dekimasu ka?

iie, muri desu. Zen zen wakaranai desu yo!

Can you solve this problem?

No, it’s impossible. I don’t understand it at all!


Sumimasen… (すみません…)

You may have heard the term “sumimasen” before with the meaning “excuse me”. 

Sumimasen is also sometimes used to express that someone does not know something in response to a question. 

In Japan, it is rare for someone to outright give a negative response. This is why in many circumstances, the “no” is outright omitted from the sentence and replaced with a “well…” or “that’s a bit…”. 

Instead of responding that they don’t know, someone speaking Japanese may simply apologize and say “sumimasen”. This is a polite way to let someone know that they do not know the answer you seek.

Example: How to use “Sumimasen” in a Sentence

英語はわかりますか?ああ, すみません…

Eigo wa wakarimasu ka?

Aa, Sumimasen…

Do you understand English?

Ah, excuse me. (I don’t know)


There are many unspoken and omitted words in Japanese, so be sure to read people’s facial expressions well while talking to get an idea of what they are trying to convey. 

It’s considered rude not to look at people when speaking anyways, so it’s doubly important!


Sore wa muzukashii desuそれは難しいです

At times, people are reluctant to outright say that they don’t know something in Japan. This is typical of customer service representatives and at the workplace, because they do not want to disappoint you. 

Instead of speaking directly and saying “I don’t know”, someone might say “sore wa muzukashii desu” meaning “That’s difficult”. 

In English, it’s similar to someone saying “Hmmm… that’s a tough one. I’m not sure!” but with more indirect words. 

This is common to the Japanese language, as speaking directly can be perceived as rude.

However, foreigners are usually given a free pass when it comes to being direct, because it is common knowledge that Japanese is an especially indirect language.

Example: How to use “Sore wa muzukashii desu” in a sentence

原宿への行き方を知っていますか?それは難しいですよね? ごめんなさい。

Harajuku e ikikata o shitte imasu ka?

Sore wa muzukashii desu yo ne? Gomen nasai.

Do you know how to get to Harajuku?

That’s a bit difficult, isn’t it? I’m sorry. 


If someone gives an apologetic look and then trails off, you can assume that the person doesn’t know the answer, or that the answer is not the one that you want to hear. 

Understanding the “context clues” of body language and tone is very important when having conversations in Japanese, because the same words can often convey many different things- just like English!