How to say "guarantee" in Japanese

• 保証ほしょうJLPT N3approx.Common
  noun, suru verb, transitive verbThe everyday word for a guarantee as a promise or assurance, such as a product warranty or a pledge that something will be done or will hold true. This is usually the word you want.
  彼女かのじょの誠実せいじつさは私が保証ほしょうします。↗

  You have my word on her sincerity.
• 担保たんぽCommon
  nounCovers 'guarantee' in the financial and legal sense of security or collateral put up against a loan or obligation. Not the word for general promises or assurances.
  家いえを担保たんぽにお金かねを借かりよう。↗

  We'll use the house as collateral so we can borrow some money.
• 保するほするCommon
  suru verb (irregular), transitive verbThe verb 'to guarantee'. When you need to say 'guarantee' as an action rather than name the guarantee itself, this is the corresponding verb form.
• 確保かくほJLPT N1approx.Common
  noun, suru verb, transitive verbMeans securing, obtaining, or ensuring something, and only touches 'guarantee' in that sense of making sure something is in hand or safe. For promises or warranties it is not the right word.
  お庭にわの方ほうにも縁台えんだいを並ならべれば、かなり座席数ざせきすうを確保かくほできそうだなーと思おもいました。↗

  I thought that if we lined up benches in the garden as well, we could achieve quite a seating capacity.
• 裏付けうらづけCommon
  nounMeans backing, proof, or evidence supporting a claim or argument. It suits 'guarantee' only when you mean something that substantiates a statement, not a promise or warranty.
  この報告ほうこくは彼かれの背信はいしんを裏付うらづけしている。↗

  This report confirms his betrayal.

Use 保証 for promises or assurances that something will work or be as stated, 担保 for financial security or collateral, 「保する」 for the verb 'to guarantee', 確保 for securing or ensuring something, and 「裏付け」 for evidence backing a claim.

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

• 保証ほしょうguarantee
• 担保たんぽsecurity
• 保するほするto guarantee
• 確保かくほsecuring
• 裏付けうらづけsupport (e.g. for an argument)
• 保証金ほしょうきんdeposit (esp. on renting a house)
• 折り紙を付けるおりがみをつけるto guarantee (someone's ability or the quality of their work)
• 請け合いうけあいassurance
• ギャランティーguaranty
• 保険ほけんguarantee
• 引き受けるひきうけるto guarantee
• 請け合ううけあうto assure
• 太鼓判たいこばんseal of approval
• 質しちpledge
• 証するしょうするto guarantee
• 証すしょうすto guarantee