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N4Lesson notes · Oct 2, 2026

Believe in Japanese: how to say 信しんじる, "I believe in you" and "I can''t believe it

"Believe" in Japanese is 信しんじる (しんじる), and "I believe in you" is 君きみを信しんじてる (きみをしんじてる) — but "I believe that…" as an opinion is usually 思おもう, not 信しんじる.

English uses one word, "believe", for three very different jobs: trusting a person, accepting that something is true, and holding an opinion. Japanese splits those jobs across several words. Once you know which job you are doing, the right word picks itself.

The basics

How do you say "believe" in Japanese?

The verb is 信しんじる (しんじる). It is a ru-verb, so it conjugates the easy way: 信しんじます (polite), 信しんじない (negative), 信しんじた (past), 信しんじて (te-form).

The thing you believe or trust takes を:

彼かれの話はなしを信しんじる。 — I believe his story. (plain form, accepting that it is true) 先生せんせいを信しんじています。 — I trust my teacher. (polite, trusting a person) 幽霊ゆうれいは信しんじない。 — I don't believe in ghosts. (plain, 〜は for contrast)

Notice that English "believe in ghosts" has no を-versus-に problem in Japanese: you simply believe the thing, so it is 幽霊ゆうれいを信しんじる or, with は for contrast, 幽霊ゆうれいは信しんじない.

How do you say "I believe in you"?

君きみを信しんじてる (casual), あなたを信しんじています (polite), or just 信しんじてるよ when it is obvious who you mean.

君きみを信しんじてる。 — I believe in you. (casual, said to a friend or partner) あなたを信しんじています。 — I believe in you. (polite, to a student, a colleague, someone you respect) お前まえを信しんじてるぞ。 — I'm counting on you. (rough and warm, male speech, anime team energy)

Why 信しんじてる and not 信しんじる? Because this belief is a state that is already going on, and Japanese marks ongoing states with the ている form. 信しんじる on its own sounds like a decision you are making right now: "I will believe it." 信しんじてる says "I am in the state of believing, and have been." That is exactly what "I believe in you" means. If the ている form is still fuzzy, read the teiru form: progressive and state first.

What about "I can't believe it"?

This is the phrase you will hear most in daily life: 信しんじられない (しんじられない).

信しんじられない! — I can't believe it! (casual exclamation, shock or amazement) 信しんじられないほどおいしい。 — It's unbelievably delicious. (natural, good surprise) こんなことが起おきるなんて、信しんじられません。 — I can't believe something like this happened. (polite, serious)

信しんじられない is the potential negative of 信しんじる ("cannot believe"), built with the same idea as the 〜ことができる potential form. It can mean good shock or bad shock; tone and context tell you which.

How do you ask someone to believe you?

Use the te-form for a request:

信しんじて! — Believe me! (casual, urgent) 信しんじてください。 — Please believe me. (polite) 本当ほんとうだよ、信しんじて! — It's true, believe me! (casual, pleading)

Beyond the basics

What is the difference between 信しんじる, 信用しんようする and 信頼しんらいする?

All three can be translated "trust", but each looks at a different thing.

Word Core idea Typical use
信しんじる Accept as true / have faith in someone Statements, people, possibilities, emotional support
信用しんようする Rely on someone's track record Money, work, practical reliability
信頼しんらいする Deep, earned trust in a relationship Partners, teams, mentors; a bit formal

彼かれの言葉ことばを信しんじる。 — I believe what he says. (信しんじる: accepting the statement) あの店みせは信用しんようできる。 — That shop can be trusted. (信用しんよう: reliable, you can do business there) 彼かれを信頼しんらいして、仕事しごとを任まかせた。 — I trusted him and left the work to him. (信頼しんらい: deep trust built over time)

A quick test: 信用しんよう is about whether you can use someone (it contains 用よう, "use"). 信頼しんらい is about leaning on someone (頼らい, "rely"). 信しんじる is the widest word and the only one that works for "I believe in you" as encouragement. Telling a friend before a match 君きみを信頼しんらいしてる sounds like a performance review; 君きみを信しんじてる sounds like a friend.

Notice the pattern with the potential form: 信用しんようできる is natural ("can be trusted"), and its negative 信用しんようできない is a strong judgment about someone's character. Use it carefully.

When should you use 思おもう instead of 信しんじる?

When you mean "I believe that…" as an opinion or a guess, Japanese uses 思おもう (おもう). 信しんじる is too strong: it sounds like faith or conviction, not a view.

明日あしたは雨あめだと思おもう。 — I believe it will rain tomorrow. (思おもう: ordinary opinion, 70% sure) 明日あしたは雨あめだと信しんじている。 — I firmly believe it will rain tomorrow. (strange; sounds like you have faith in the weather) 彼かれはもう来きていると思おもいます。 — I believe he has already come. (polite opinion)

The English "I believe that…" is often just a polite way of saying "I think". Translate it as と思おもう. The full story of that pattern, including how it softens statements, is in と思おもいます: how to say "I think" in Japanese.

信しんじる takes over when you are not stating a probability but placing trust: 勝かてると信しんじている, "I believe we can win", is not a forecast, it is faith.

勝かてると信しんじている。 — I believe we can win. (conviction, not prediction)

How do you react with "no way!"?

Often you do not say 信しんじられない at all. Short reactions cover the same emotion:

まさか! — No way! (casual, "that can't be true!") うそでしょ? — You're kidding, right? (casual, literally "that's a lie, isn't it?") マジで? — Seriously? (very casual, see below) ありえない! — Impossible! / No way! (casual, "that can't exist")

まさか expresses "I never expected this", and it also works before a guess: まさか、君きみが? (no way, you?). うそでしょ is the everyday workhorse. 本当ほんとうに and マジで ask for confirmation; if you want more on those, see hontou ni. For the wider family of shock words, see surprised in Japanese.

What is the opposite of 信しんじる?

疑うたがう (うたがう) means "to doubt" or "to suspect".

彼かれの話はなしを疑うたがっている。 — I doubt his story. (polite-ish, ている for ongoing doubt) 友ともだちを疑うたがいたくない。 — I don't want to doubt my friend. (casual, 〜たくない) 疑うたがってごめん。 — Sorry for doubting you. (casual, apology)

The noun is 疑うたがい (うたがい), "doubt". Related: 疑問ぎもん (ぎもん), "a question mark / doubtful point". The pair 信しんじる and 疑うたがう works like "trust" and "suspect" in English.

Where does 信仰しんこう fit?

信仰しんこう (しんこう) is religious faith. You will meet it in news and in discussion of religion, but not in friendly chat: 信仰しんこうを持もつ, "to have faith". A related everyday word is 信しんじる itself in religious use (神かみを信しんじる, "to believe in God"), so you rarely need 信仰しんこう unless you are writing or discussing religion.

How does it sound in anime?

Friendship speeches are the home of 信しんじてる. The pattern is nearly always a short, direct line, often with a pause before it:

仲間なかまを信しんじてるから。 — Because I believe in my friends. (typical shonen reason for a risky move) お前まえが信しんじてくれるなら、俺おれも信しんじる。 — If you believe in me, I'll believe too. (rough male speech, くれる for "you do this for me") 私わたしは、あなたを信しんじてる。 — I believe in you. (slow, heartfelt, the quiet-heroine version)

The grammar trick to listen for: 信しんじてる (ongoing state) in warm moments, 信しんじる (plain, decisive) when someone makes a vow, and 信しんじない when a character shuts the door. A hero never says 信しんじたい unless he is struggling: 信しんじたい means "I want to believe", which admits doubt.

信しんじたいんだ。 — I want to believe. (admitting you cannot quite do it yet)

Promises and belief often travel together: "I believe you, so promise me." If you want that side, read promise in Japanese: 約束やくそく.

Common mistakes

  • Using 信しんじる for ordinary opinions. "I believe it's going to rain" should be 雨あめが降ふると思おもう. 信しんじる sounds like you have faith in the forecast.
  • Saying 信しんじる when you mean "I believe in you" right now. Use 信しんじてる / 信しんじています. The plain form sounds like a decision rather than a state.
  • Choosing 信頼しんらい for encouragement. 君きみを信頼しんらいしてる is a manager's sentence. Between friends, 信しんじてる is warmer.
  • Forgetting that 信しんじられない is a set phrase. Do not build 信しんじれない from the ra-removed colloquial form in writing or polite speech. 信しんじられない is the standard form.
  • Using 疑うたがう for "I wonder". "I wonder if it will rain" is 雨あめが降ふるかな, not 疑うたがう. 疑うたがう means active doubt or suspicion.

Practice

Build each answer before opening it. Questions 3 and 4 are a pair, and so are 5 and 6.

1. How do you say "I believe in you" casually, to a friend?

Show answer

君きみを信しんじてる — ている marks the ongoing state of believing, which is what "I believe in you" means.

2. Why is 君きみを信しんじる (without てる) less natural for "I believe in you"?

Show answer

It sounds like a decision made right now. The state of already trusting someone is expressed with 信しんじている or 信しんじてる.

3. Say "I believe it will rain tomorrow" as a plain opinion.

Show answer

明日あしたは雨あめだと思おもう — an everyday opinion or guess uses 思おもう.

4. Say "I believe we can win" as an act of faith, not a forecast.

Show answer

勝かてると信しんじている — 信しんじる carries conviction, not probability. This is the pair to question 3.

5. Which word fits: "That shop can be trusted" (reliable for business)?

Show answer

信用しんよう — あの店みせは信用しんようできる. 信用しんよう is about whether you can rely on someone's track record.

6. Which word fits: "I trust my mentor deeply, after years working together"?

Show answer

信頼しんらい — 師匠ししょうを信頼しんらいしている. 信頼しんらい is deep, earned trust in a relationship. This is the pair to question 5.

7. How do you say "I can't believe it!" in one word of grammar plus ない?

Show answer

信しんじられない — the potential negative of 信しんじる, "cannot believe".

8. Your friend tells you something shocking. Give a short casual reaction that does not use 信しんじる at all.

Show answer

まさか! / うそでしょ? / ありえない! — each expresses "no way" without the verb. うそでしょ is the everyday workhorse.

9. What is the opposite of 信しんじる, and how do you say "I doubt his story"?

Show answer

疑うたがう — 彼かれの話はなしを疑うたがっている — 疑うたがう means doubt or suspect, and ている shows the ongoing doubt.

10. What does 信しんじたい mean, and what does it admit?

Show answer

"I want to believe" — and it admits that you cannot quite believe yet. It is often the line of a character who is struggling.

In a trial lesson, say 君きみを信しんじてる to a friend and 信しんじられない about a surprise, and use 思おもう rather than 信しんじる when you are simply giving an opinion.

FAQ

Is 信しんじる the same as "believe in" in English? Mostly, but the English phrase covers three jobs. Trusting a person is 信しんじる or 信頼しんらいする, accepting a statement as true is 信しんじる, and holding an opinion is と思おもう.

Can I say 信しんじてください to a boss? Yes, 信しんじてください is polite and fine. For a very formal request, 信しんじていただけませんか is softer.

What is the difference between 信しんじられない and 信しんじない? 信しんじない means "I don't believe it" (a decision to reject). 信しんじられない means "I can't believe it" (emotional shock, or inability to accept). 信しんじられない can be positive, as in 信しんじられないほどきれい, "unbelievably beautiful".

Is 信用しんよう or 信頼しんらい stronger? 信頼しんらい is deeper and more personal. 信用しんよう is more practical: it is what you give a shop, a bank or a coworker's work. Friends and partners get 信頼しんらい and 信しんじる.

How do I say "believe in yourself"? 自分じぶんを信しんじて (casual) or 自分じぶんを信しんじてください (polite). It is the standard pep-talk phrase, in anime and in real life.

Is マジで a good way to say "really?" Yes, among friends. マジで? means "seriously?" and is more casual than 本当ほんとうに. Use 本当ほんとうに or そうですか in polite settings.

Vocabulary from this article

Tap the block to select all of it, then copy. In Anki: File → Import, note type Basic, separator Tab.

信じる	しんじる — to believe, to trust
信用する	しんようする — to trust (reliability)
信頼する	しんらいする — to trust deeply
信仰	しんこう — religious faith
疑う	うたがう — to doubt, to suspect
思う	おもう — to think, to believe (opinion)
幽霊	ゆうれい — ghost
仲間	なかま — comrade, friend
勝つ	かつ — to win
まさか	まさか — no way
うそでしょ	うそでしょ — you're kidding
ありえない	ありえない — impossible, no way
自分	じぶん — oneself

I'm Yuuki, a Japanese teacher based in Tokyo. I've taught on italki as a Top 1% teacher and watched over 1,500 anime, so most of the example sentences on this blog come from lines I've actually heard students ask about, including these. For practice with feedback, Book a trial lesson · $13.

Sources: the author's own lessons and standard reference grammars.

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