How to say "attentive" in Japanese

• 注意深いちゅういぶかいCommon
  i-adjectiveCovers 'attentive' in the sense of paying close, alert attention: watchful, cautious, careful not to overlook anything. Fits observing, examining, or handling something where a careless mistake would matter.
• 念入りねんいりCommon
  na-adjective, nounReally means 'thorough, scrupulous, conscientious': doing something with painstaking care. For 'attentive' it is only a marginal match — seldom the word you want unless you mean meticulous attention to how a task is done.
  ジョンは、念入ねんいりにその事故じこを調査ちょうさした。↗

  John investigated the accident thoroughly.

Choose 「注意深い」 when 'attentive' means watchful, alert, and careful not to miss or overlook anything; 「念入り」 is really 'thorough and painstaking', fitting 'attentive' only for care lavished on how a task is done.

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

• 注意深いちゅういぶかいattentive
• 念入りねんいりcareful
• 気の利くきのきくattentive
• 細やかこまやかmeticulous
• 細かいこまかいsensitive