How to say "investigation" in Japanese

• 研究けんきゅうJLPT N4approx.Common
  noun, suru verb, transitive verbCovers investigation in the sense of systematic research or study, especially academic or scientific work aimed at deeper knowledge. It is not the word for an official inquiry into an incident or someone's conduct.
  私はエイズの研究けんきゅうに従事じゅうじしている。↗

  I am engaged in AIDS research.
• 調査ちょうさJLPT N3approx.Common
  noun, suru verb, transitive verbThe usual word for an investigation as fact-finding: looking into a matter, incident, or situation to establish the facts, whether by officials, companies, or researchers.
  その調査ちょうさは進行中しんこうちゅうです。↗

  The investigation is under way.
• 検討けんとうJLPT N3approx.Common
  noun, suru verb, transitive verbReally means examination or consideration of a plan, proposal, or problem before deciding; when English 'investigation' refers to this kind of deliberative study, this is the word, not a fact-finding inquiry.
  私わたしたちはその件けんを詳細しょうさいに検討けんとうした。↗

  We debated the matter at length.
• 調べしらべJLPT N1approx.Common
  noun, noun (suffix)Investigation as the act of looking into or checking something; as the noun form of the verb 'to look into', it also serves for inspection and examination.
  先生せんせいはわれわれの答案とうあん調しらべに忙いそがしい。↗

  The teacher is busy looking over our tests.
• 追及ついきゅうJLPT N1approx.Common
  noun, suru verb, transitive verbInvestigation specifically aimed at someone's guilt or responsibility, with a strong flavor of questioning, pressing, or hounding the person involved; not a neutral fact-finding inquiry.
  追及ついきゅうされて、つい、見え透みえすいた嘘うそをついてしまった。↗

  I was pressed by their questioning and slipped into telling an obvious lie.

Use 調査 for fact-finding inquiries, 研究 for scholarly or scientific research, 検討 for examining a plan or proposal, 「調べ」 for checking or looking into something, and 追及 for pursuing someone's guilt or responsibility.

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

• 研究けんきゅうresearch
• 調査ちょうさinvestigation
• 検討けんとうconsideration
• 調べしらべinvestigation
• 追及ついきゅうinvestigation (e.g. into someone's guilt)
• 取り調べとりしらべinvestigation (e.g. by police or prosecutors)
• 究明きゅうめいinvestigation (esp. in academic and scientific contexts)
• 捜査そうさsearch (esp. in criminal investigations)
• 探究たんきゅうresearch
• 査察ささつinspection (for compliance)
• 探索たんさくsearch
• 審査しんさjudging
• 考察こうさつconsideration
• 探査たんさprobe
• 調べものしらべものinvestigation
• 討究とうきゅうinvestigation
• 考究こうきゅうinvestigation
• 勘検かんけんinvestigation
• 勘査かんさinvestigation
• 原因調査げんいんちょうさinvestigation (to determine the cause of something)
• 推問すいもんinvestigation (e.g. crime)
• プローブprobe
• 事情聴取じじょうちょうしゅinquiry
• 検討作業けんとうさぎょうreview work
• 詮索せんさくinquiry into
• 検視けんしinvestigation (e.g. of a crime scene)
• 詮議せんぎinvestigation (into a suspect)
• 改めあらためexamination