Translation guide
The phrase 'at one time' is used to refer to a past period, often implying that the situation has since changed. It can also mean 'simultaneously' or 'formerly'. This guide covers natural Japanese expressions for each use.
To say that something was true or happened during a period in the past, but is no longer the case.
A common and natural way to say 'at one time' meaning 'formerly'. Often used with past tense verbs and implies a contrast with the present.
かつてはここに大きな森があった。
At one time, there was a large forest here.
He was at one time a famous singer.
Literally 'at one time/period', often used for a temporary past state or situation that has changed. Slightly more concrete than かつては.
一時は会社を辞めようと思った。
At one time I thought about quitting my job.
Means 'previously' or 'before'. Can be used similarly to 'at one time' when contrasting past and present.
以前はこの辺りは静かだった。
At one time this area was quiet.
Means 'long ago' or 'in the old days'. Can be used for 'at one time' when referring to a distant past, but may sound too vague or nostalgic for recent changes.
昔はこの町に映画館があった。
At one time there was a movie theater in this town.
To indicate that multiple things happen or are done at the same time.
Means 'all at once' or 'at the same time'. Used when multiple actions or things occur simultaneously.
一度に二つのことはできない。
I can't do two things at one time.
一度にたくさんの人が入ってきた。
Many people came in at one time.
Means 'simultaneously' or 'at the same time'. More formal than 一度に, often used for events occurring concurrently.
Means 'all at once' or 'in unison', often used when a group does something together at the same moment.
To refer to an unspecified time in the past, often in narratives or when the exact time is unknown.
Literally 'a certain time', used to introduce an event that happened at some point in the past without specifying when.
ある時、彼は突然姿を消した。
At one time, he suddenly disappeared.
Without は, かつて can mean 'once' or 'at one time' in a more literary or narrative style. Often used with ～たことがある.
かつては emphasizes a past state that is no longer true, often with a sense of nostalgia or contrast. 一時は focuses on a temporary period, often implying that the situation was not permanent and has since changed. 一時は can also be used for future hypotheticals (e.g., 一時はどうなるかと思った 'For a moment I wondered what would happen'), while かつては is strictly past.
Do not translate 'at one time' word-for-word as 一つの時間に or ある一つの時に. These are not natural Japanese. Use the phrases above depending on the intended meaning.
二つの会議が同時に行われた。
Two meetings were held at one time.
生徒たちが一斉に立ち上がった。
The students stood up at one time.
At one time I heard such a story.