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ukkari kaigi no zikan wo matigaete simaimasita.

うっかり　会議かいぎ　の　時間じかん　を　間違まちがえて　しまいました。ukkari kaigi no zikan wo matigaete simaimasita.
I accidentally got the meeting time wrong.
FromLesson 26inHardcore Japanese
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Questions & Answers about ukkari kaigi no zikan wo matigaete simaimasita.

What does the word うっかり do here? Is it an adverb, and does it need any particle?

うっかり is an adverb meaning “carelessly,” “absent‑mindedly,” or “by oversight.” It directly modifies the action and does not take a particle. You can put it at the start or right before the verb phrase:

  • うっかり会議の時間を間違えてしまいました。 You’ll also see うっかりして when it’s linked to the following clause:
  • うっかりして鍵を忘れました。
Why is の used between 会議 and 時間?
の marks an attributive/possessive relationship: 会議の時間 = “the time of the meeting.” It’s like “meeting’s time.” This structure is very common: 会社の住所 (company’s address), 日本の文化 (Japan’s culture), etc.
Why is を used after 時間? Could another particle be used?
間違える takes a direct object with を. The pattern is “X を 間違える” = “to get X wrong.” Here, 時間 (the meeting time) is what was gotten wrong, so 時間を is required. Using に would change the meaning to “at the time of the meeting,” which isn’t the point here.
What nuance does the てしまいました add?
〜てしまいました signals completion and often implies an unintended result or regret. So 間違えました is neutral “(I) made a mistake,” while 間違えてしまいました adds “I (regrettably/accidentally) made a mistake.” Context decides whether the nuance is just completion or also “oops/regret.”
Who is the subject? Why isn’t “I” stated?

Japanese commonly drops obvious subjects. In this context it’s understood as “I.” If you want to make it explicit, you can add 私は:

  • 私はうっかり会議の時間を間違えてしまいました。 Using が (私が) strongly marks “I (as the one who)” and is less typical unless you’re contrasting with someone else.
What’s the difference between 間違える and 間違う? Which should I use?
  • 間違える is transitive: it regularly takes an object with を. Example: 答えを間違える (to get the answer wrong).
  • 間違う functions both intransitively and transitively in modern Japanese. You’ll hear 答えを間違う and 時間を間違う in everyday speech. In your sentence you can say either:
  • 会議の時間を間違えてしまいました。 (using 間違える)
  • 会議の時間を間違ってしまいました。 (using 間違う) Both are natural; 間違える sounds a touch more “textbook,” but both are fine.
Can I drop うっかり or てしまいました? How does it change the feel?
  • Without うっかり: 会議の時間を間違えてしまいました。 → emphasizes unintended/regretful result.
  • Without てしまいました: うっかり会議の時間を間違えました。 → emphasizes carelessness but is more neutral about regret.
  • Without both: 会議の時間を間違えました。 → plain statement, no extra nuance. Add an apology if needed: 申し訳ありません。
How would I make this more casual or more formal?
  • Casual: うっかり会議の時間、間違えちゃった。 or 会議の時間を間違えちゃった。
  • Polite standard (your sentence): うっかり会議の時間を間違えてしまいました。
  • Business‑polite/apologetic (softer than saying “careless”):
    会議の時間を勘違いしておりました。申し訳ございません。
    or 確認不足で会議の時間を間違えてしまいました。申し訳ございません。
    Note: In formal apologies, explicitly saying うっかり can sound too frank; framing it as 勘違い or 確認不足 is often preferred.
Can I say 会議の時間に instead of 会議の時間を?
No, not for this meaning. 時間に would mean “at the time of the meeting.” You need を because the time itself is the thing you got wrong: 時間を間違える.
Does うっかり ever take と, like うっかりと?

You may see うっかりと in writing, but in everyday speech うっかり (without と) is standard. Related word: つい (“just/without thinking”) often modifies intentional actions (e.g., eating, saying something). うっかり highlights an oversight.

  • つい言ってしまった。 (I blurted it out.)
  • うっかり言ってしまった。 (I carelessly said it.)
Does 〜てしまいました always imply regret?

No. It mainly marks completion; regret/unintended is frequent but depends on context.

  • 宿題を全部やってしまいました。 (I finished all my homework.) → completion (could be neutral/satisfied).
    With mistakes or losses, it naturally suggests “oops/regret.”
Can I move うっかり around in the sentence?

Yes, within reason. These are all natural:

  • うっかり会議の時間を間違えてしまいました。
  • 会議の時間をうっかり間違えてしまいました。
  • うっかりして会議の時間を間違えてしまいました。 Avoid putting it after the verb; it’s an adverb and goes before the action.
How do I say what I mistook the time for (e.g., “I thought it was 9:00”)?

Use the pattern “X を Y と 間違える / 勘違いする”:

  • 開始時間を9時と勘違いしていました。
  • 会議の時間を9時と間違えてしまいました。 You can also use 〜だと with 勘違い: 9時だと勘違いしていました。
Are there any synonyms for 間違える that fit here?
  • 勘違いする (to misunderstand, misremember): 会議の時間を勘違いしました。
  • 取り違える (to mix up one thing for another): use when confusing two specific times, e.g., 10時と12時を取り違えました。
  • ミスをする (to make a mistake): 会議の時間でミスをしてしまいました。 (broader/less direct)
Why are there spaces between the words in the original sentence?

They’re just for learners’ readability. In normal Japanese you write it without spaces:
うっかり会議の時間を間違えてしまいました。

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