Translation guide
The English phrase "break down" has several distinct meanings. This guide covers the most common ones for learners: mechanical failure, emotional collapse, analysis into parts, and physical decomposition. Each meaning has different natural Japanese expressions.
To stop functioning (machines, vehicles, systems)
General intransitive verb for something breaking or becoming out of order. Used for machines, electronics, etc.
車が壊れた。
My car broke down.
エアコンが壊れてしまった。
The air conditioner broke down.
More formal/technical term for malfunction or breakdown. Often used in written contexts or official announcements.
エレベーターが故障しています。
The elevator is out of order.
Literally 'stops moving'. A natural, slightly casual way to say something broke down.
パソコンが動かなくなった。
My computer broke down.
To lose control of one's emotions, start crying, or have a mental health crisis
To break down in tears, collapse crying. Emphasizes the physical act of crying uncontrollably.
彼女は悲しい知らせを聞いて泣き崩れた。
She broke down when she heard the sad news.
To be mentally overwhelmed or broken down. '参る' is a humble verb meaning to be defeated/affected.
仕事のストレスで精神的に参ってしまった。
I broke down mentally from work stress.
To become unable to control one's emotions. A more descriptive phrase.
彼は感情が抑えられなくなって、大声で泣き出した。
He broke down and started crying loudly.
To separate something into smaller parts for analysis or understanding
To break down, disassemble, or analyze into components. Used for physical objects, data, arguments, etc.
このレポートでは、問題を細かく分解して説明します。
In this report, we will break down the problem in detail.
データを項目ごとに分解する。
Break down the data by category.
To divide into small parts. More casual and concrete than 分解する.
作業を細かく分けて、順番にやろう。
Let's break down the task into smaller steps and do them in order.
To rot, decay, or be destroyed into basic elements
Also used for chemical/biological breakdown. Context distinguishes from analysis meaning.
プラスチックは自然に分解されない。
Plastic doesn't break down naturally.
To rot, go bad (organic matter). More specific than general breakdown.
生ゴミが腐って臭い。
The garbage has broken down and smells.
The English phrasal verb 'break down' does not have a single Japanese equivalent. Always choose the expression that matches the intended meaning (mechanical, emotional, analytical, etc.). Using 壊れる for emotional breakdown would be unnatural.