How to say "insane" in Japanese

• 狂的きょうてき
  na-adjectiveCovers insane in the sense of frenzied or fanatical — behavior, zeal, or devotion carried beyond reason. Less common, and closer to 'fanatic' than to everyday 'crazy'; seldom the word for calling a person nuts.
• 頭がおかしいあたまがおかしい
  expression, i-adjectiveThe direct statement that someone is insane or out of their mind: their head is off. Fits a person whose talk or behavior strikes you as genuinely crazy.
  あの老人ろうじんは頭あたまがおかしいにちがいない。↗

  That old man must be off his rock.
• 気が変きがへん
  na-adjectiveRefers to a mind that has gone wrong — mad, crazy, light in the head. Suits someone who seems driven out of their mind, say by grief or shock, rather than mere silliness.
• 頭のおかしいあたまのおかしい
  expression, prenominal modifierThe noun-modifying counterpart of 頭がおかしい, with the same sense: insane, crazy, nuts, out of one's mind. Use it when you describe someone as crazy inside a sentence rather than assert it flatly.
• あたおか
  na-adjectiveCasual slang for 'nuts', a shortened form of 頭がおかしい. Fits relaxed banter — reacting to a wild remark or plan by calling it crazy — rather than serious description.

For a person who seems out of their mind, use 「頭がおかしい」 (as a statement) or 「頭のおかしい」 (modifying a noun); 「気が変」 suggests a mind gone deranged, 狂的 leans toward frenzied fanaticism, and 「あたおか」 is casual slang for 'nuts'.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 狂的きょうてきinsane
• 頭がおかしいあたまがおかしいinsane
• 気が変きがへんinsane
• 頭のおかしいあたまのおかしいinsane
• あたおかinsane
• 頭おかしいあたまおかしいinsane
• 正気とは思えないしょうきとはおもえないnot in one's right mind
• 病気びょうきcrazy
• 規格外きかくがいexceptional
• やばいcrazy
• 激ヤバげきやばcrazy