Translation guide
This guide covers how to express the idea of 'one part' in Japanese, including literal fractions, portions, components, and roles.
Referring to a single segment, piece, or fraction of something.
The most common and versatile way to say 'one part' or 'a part'. Can be used for physical parts, portions, or abstract components.
このケーキの一部をどうぞ。
Please have one part of this cake.
その話は一部しか知らない。
I only know one part of that story.
Emphasizes 'one portion' or 'a part' more explicitly than 一部. Often used when contrasting with the whole.
この書類の一部分を修正してください。
Please correct one part of this document.
Literally 'one piece' or 'a fragment'. Used for small, often broken-off parts. Somewhat literary.
ガラスの一片が床に落ちていた。
One part of the glass had fallen on the floor.
Specifying a proportion, such as in recipes or solutions.
Pattern for 'one part of X'. Use with counters or just the number 1. Often used in technical contexts.
水1に対して酢1の割合で混ぜる。
Mix one part water to one part vinegar.
Directly means '1 part' in recipes or formulas. Often used with ～部 (e.g., 2部 for two parts).
小麦粉1部と砂糖1部を加える。
Add one part flour and one part sugar.
Referring to a share of work or responsibility.
Means 'role' or 'part'. Use with 一つの (one) to specify 'one part/role'.
彼はプロジェクトで一つの役割を担っている。
He plays one part in the project.
Means 'share' or 'allotment'. Often used in work contexts. 一つの分担 means 'one part of the division of labor'.
A single component or spare part.
Standard word for 'part' or 'component' of a machine. Use with 一つの (one) or counter 一個 (いっこ).
この部品が壊れています。
This one part is broken.
Loanword from English 'parts'. Common in casual or technical contexts, especially for electronics or cars.
In many contexts, Japanese uses counters or specific nouns instead of directly translating 'one part'. For example, 'one part of a book' is usually 本の一部 (ほんのいちぶ) or 本の一章 (ほんのいっしょう) if it's a chapter. Always consider what kind of 'part' you mean.
各自が一つの分担をこなす。
Each person handles one part.
Where can I buy this one part?