Mastering Japanese: How to Say I Don’t Know in Quick Steps

If you’re learning Japanese, one of the essential phrases you’ll need to master is “I don’t know.” Being able to express uncertainty or lack of knowledge can come in handy in various situations and significantly enhance your language skills. In this section, we will explore different ways to say “I don’t know” in Japanese, from the most basic to the more casual and specialized expressions.

Whether you’re a complete beginner or an intermediate learner, our guide will provide you with useful tips to improve your Japanese language skills. So, let’s get started with the basics and learn how to express “I don’t know” in Japanese. By the end of this section, you’ll be able to confidently say this essential phrase in various contexts.

So, how do you say “I don’t know” in Japanese? Let’s find out.

The Basics: Japanese Translation for I Don’t Know

Japanese language has several ways to express uncertainty or lack of knowledge. In this section, we will cover the fundamental translations for “I don’t know” in Japanese.

Japanese Romaji English Translation
知りません Shirimasen I don’t know
わかりません Wakarimasen I don’t understand
分かりません Wakarimasen I don’t know

“Shirimasen” is the most straightforward way to say “I don’t know” in Japanese, and it is suitable for most situations. “Wakarimasen” can also mean “I don’t know” but it emphasizes not understanding something.

“Wakarimasen” can be used when someone is asking you to provide an explanation or seeking clarity on something you are saying.


“Wakarimasen” is not appropriate if someone asks you a factual question that you genuinely don’t know the answer to. In such cases, use “Shirimasen” instead.

Polite Expressions: Ways to Say I Don’t Know with Respect

When it comes to expressing uncertainty or lack of knowledge in formal or professional contexts, it’s essential to use polite language. Here are some polite expressions for saying “I don’t know” in Japanese:

Japanese Phrase English Translation
申し訳ありませんが、わかりません。 “I’m sorry, but I don’t know.”
恐れ入りますが、お答えできません。 “I’m sorry, but I cannot answer.”
大変申し訳ありませんが、お答えできません。 “I’m very sorry, but I cannot answer.”

Using these expressions will convey your respect and humility in formal situations. It’s important to note that when speaking to someone of higher status or authority, it’s appropriate to use the polite form of Japanese.

For example:

Informal Formal
わかんない。 わかりません。
知らない。 存じ上げません。

Using the appropriate level of formality will ensure that you convey your message accurately and respectfully.


Politeness is a crucial aspect of Japanese language and culture. When expressing uncertainty or lack of knowledge, it’s important to use polite language appropriate for the situation. These polite expressions will help you convey your message respectfully in formal or professional contexts.

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Casual Informality: Expressing I Don’t Know Casually

When engaging in casual conversations with friends or peers, it’s essential to know how to say “I don’t know” informally. Here are some common phrases used in casual settings:

Phrase Translation
しらない shiranai
知らん shiran
わかんない wakannai

These phrases are more commonly used among friends or in informal settings. They are less polite than other expressions and should be used cautiously in professional settings.

Another way to express uncertainty informally is to use the phrase “no idea” in Japanese:

Phrase Translation
全然わからない zenzen wakaranai

This phrase translates to “I have no idea” and is a more relaxed way to express uncertainty with friends or peers.

Remember that context is key when using informal expressions, consider the situation and the person you’re speaking with before using them.

Using Casual Phrases for “I Don’t Know” in Japanese

When using informal phrases to express uncertainty, it’s essential to pay attention to your tone of voice and body language. Using the wrong tone can make you come off as disinterested or disrespectful. Similarly, nonverbal cues such as shrugging or shaking your head can convey your uncertainty to your audience.

Here are some examples of how to use these informal expressions:

  • “しらない” – “shiranai”: You can use this phrase to answer a question you don’t know the answer to. For example, if someone asks you what the weather will be like tomorrow and you’re unsure, you can say “しらない” to indicate that you don’t know.
  • “知らん” – “shiran”: This phrase is a shortened version of “しらない” and is commonly used in casual conversations. You can use this phrase to indicate that you don’t know something or to express a lack of interest in the topic.
  • “わかんない” – “wakannai”: This phrase is similar to “しらない” and is a more relaxed way of expressing uncertainty. You can use this phrase when you’re unsure of something or don’t understand the topic.

Remember that using informal expressions to express uncertainty is appropriate in certain contexts, but it’s important to use them with caution. In professional contexts, it’s usually better to use a more formal expression to convey your lack of knowledge.

Other Contextual Expressions: Conveying I Don’t Know in Specific Situations

Aside from the standard phrases for saying “I don’t know,” there are other contextual expressions that you can use to convey uncertainty or lack of knowledge in specific situations.

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When asked a difficult question:

If you are faced with a question that you find challenging to answer, you can use the phrase “sore wa wakarimasen,” which translates to “I don’t understand that.” This expression indicates that the question is too difficult for you to comprehend or answer.

When asked about someone’s whereabouts:

If you are unsure where a person is or cannot provide an answer to their whereabouts, you can use the phrase “shiranai,” which translates to “I don’t know.” This expression is commonly used when asked about someone’s location or plans.

When asked about specific details:

If you are asked for specific details, such as a phone number or address, and you cannot provide an answer, you can use the phrase “chotto machigatteimashita,” which translates to “I’m a little mistaken.” This expression indicates that you are not entirely sure of the information and may need to recheck it.

By using these contextual expressions, you can better communicate your lack of knowledge or uncertainty in specific situations.

Remember, mastering how to say “I don’t know” in Japanese will significantly enhance your language skills and allow you to navigate various situations with ease.


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

A: There are several ways to say “I don’t know” in Japanese, depending on the level of formality and the context. Some common phrases include “wakarimasen” (わかりません), “shirimasen” (知りません), and “wakaranai” (わからない).

Q: What is the polite way to say “I don’t know” in Japanese?

A: To convey “I don’t know” politely in Japanese, you can use phrases like “wakarimasen deshita” (わかりませんでした) or “shirimasen deshita” (知りませんでした). These expressions show respect and are suitable for formal or professional contexts.

Q: How do I express “I don’t know” casually in Japanese?

A: In casual conversations or among friends, you can use more informal expressions for “I don’t know.” Some examples include “wakannai” (わかんない), “shiranai” (知らない), or simply saying “mou” (もう) which means “don’t know” in a casual sense.

Q: Are there other ways to convey “I don’t know” in Japanese?

A: Yes, depending on the specific situation, there are different contextual expressions for saying “I don’t know” in Japanese. For example, you can use phrases like “kotae ga wakaranai” (答えがわからない) to express not knowing the answer or “shiranakatta” (知らなかった) to indicate not knowing something in the past.

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