What is the difference せいとう, せいかい and ただしい? You Need

Yuka

I keep seeing 正当, 正解, and 正しい all meaning something like ‘correct’ or ‘right.’ Are they really that different?

Rei

Very different! 正しい is a general adjective for correct/right. 正解 is the right answer to a specific question. 正当 is about legitimacy or being justified. Let me show you how each one works.

Three Japanese words all containing the character 正 (right/correct) — yet each one operates in a completely different domain. Getting them right will sharpen your precision significantly.

正しい (ただしい): Correct / Right / Proper

正しい is a versatile i-adjective meaning correct, right, proper, or accurate. It can describe facts, behavior, grammar, posture — anything that conforms to the correct standard.

正しい is the broadest of the three — it works in nearly any ‘correct/right’ context.

Yuka

So 正しい is the everyday word for ‘correct’ — like saying something is right?

Rei

Yes, it’s the most versatile. If you’re not sure which word to use, 正しい is usually safe.

正解 (せいかい): The Correct Answer

正解 specifically means the correct answer to a specific question, problem, or puzzle. It implies there is a definitive right answer to be found. It’s a noun — so it’s used differently from 正しい.

Standalone 正解！ is one of the most satisfying things to hear in a quiz or game — it’s the ultimate confirmation.

Yuka

So 正解 is specifically for question-and-answer situations — quizzes, problems, exams?

Rei

Right! And it’s always a noun. You can’t say 正解な or 正解い — you use it as a noun or in compounds.

正当 (せいとう): Legitimate / Justified / Warranted

正当 is about legitimacy and justification — whether something is legally, ethically, or logically justified or warranted. It’s a more formal or legal word than the others.

Key phrase: 正当防衛 (seito bouei) = justifiable self-defense — a legal term you’ll encounter often.

Side-by-Side Comparison

Quick Quiz

正しい, 正解, or 正当?

1. 彼の行動には___な理由がある。(His actions have a legitimate reason.)
2. クイズの___は「東京」です。(The correct answer to the quiz is Tokyo.)
3. ___な文法を使ってください。(Please use correct grammar.)

Answers: 1. 正当 (legitimate) 2. 正解 (right answer) 3. 正しい (correct general usage)

Summary

Yuka

正解！ I now understand all three words perfectly!

Rei

And notice — you just used 正解 perfectly, as a standalone exclamation for ‘correct answer.’ You’ve got all three!

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