How to say "effective" in Japanese

• 有効ゆうこうJLPT N3approx.Common
  na-adjective, nounCovers 'effective' in the sense of valid or in force — a passport, ticket, or contract that still counts — and can also describe means or measures that genuinely work.
  その切符きっぷは一いち週間しゅうかん有効ゆうこうです。↗

  The ticket is valid for a week.
• 効果的こうかてきCommon
  na-adjectiveCovers 'effective' in the sense of producing the desired result — an effective method, treatment, or way of doing something; it stresses that something works well and delivers results.
  その方法ほうほうは粗雑そざつなものであったが、効果的こうかてきだった。↗

  The method was crude, but very effective.

Choose 有効 when 'effective' means valid or in force, as with documents, tickets, or agreements, and 効果的 when it means producing the desired result, as with methods or treatments.

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

• 有効ゆうこうvalid
• 効果的こうかてきeffective
• エフェクティブeffective