How to say "annex" in Japanese

• 付録ふろくJLPT N1approx.Common
  nounReally 'appendix' or 'supplement': extra material issued with a book, magazine, or newspaper, and its 'annex' sense refers to such printed extras. It does not describe an annex building or office.
• 別館べっかんCommon
  nounThe building sense: a secondary building standing apart from the main one, as with a hotel or museum annex. For 'annex' in its architectural sense, this is the word you want.
  別館べっかんは本館ほんかんの北側きたがわにある。↗

  The annex is on the north of the original building.
• 別紙べっしCommon
  nounA sheet or document attached separately to a letter, contract, or form — an enclosure. When English 'annex' means accompanying paperwork rather than a building, this is the word that fits.
  別紙べっしの注文書ちゅうもんしょの通とおり注文ちゅうもんいたします。↗

  I have enclosed your order form.
• 新館しんかんCommon
  nounAn annex that is specifically a new building: a recently built addition standing alongside a facility's original main structure. It suits 'annex' when newness matters; for an older secondary building it sounds off.
• 分室ぶんしつCommon
  nounAn annex as a separate room or office: a detached branch room belonging to an institution, set apart from its main premises. It is not the word for a whole building or an attached document.

Use 別館 for an annex building, 新館 when it is a new addition, 分室 for a detached office or room, 別紙 for a document attached to another, and 付録 for an appendix or supplement in a publication.

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

• 付録ふろくappendix
• 別館べっかんannex (to a building)
• 別紙べっしenclosure
• 新館しんかんnew building
• 分室ぶんしつdetached office
• 加えるくわえるto add
• 分館ぶんかんannex (to a building)
• アネックスannex
• 付設ふせつannex
• 副文ふくぶんaddendum (to a treaty or contract)