I think this is a question I should have asked a long time ago.. What is the difference between 案外 and 意外? What does the correct situation look like when using either?

Example with 案外:


Example with 意外:


The English translation definitely didn't help me with this one, as both are "unexpectedly". Is there a certain degree that is associated with each?


3 Answers 3


I've always thought of them in terms of their kanji make-up.

  • : can mean "plan/expectation"
  • : can mean "idea/mind/thought" (with the thought process maybe implying some subjectivity)

From there:

  • 案外:

    • "not according to plans/expectations"
    • "[contrary to/against] expectations"
    • often, but not always "disappointing(ly)"
  • 意外(に・と):

    • "[against/not] what was [thought/expected]"/"(I/you) wouldn't have thought"
    • "surprising(ly)"

Daijisen has some usage notes differentiating the two in the definition for 案外. I think it basically says:

  • 案外 is used when expectations/situations turn out different:

    I had [expectations/hopes], but it was a disappointingly boring movie.

    I was worrying, but contrary to expectations, the job was easy.

  • 意外な/意外に are used when the reality is different to what was thought, or with things that can't be expected:

    Time passed surprisingly quickly.

  • 意外 "unexpectedly"
  • 案外 "after all", "unexpectedly in such a way that something is inferior than it was originally thought"

Implication: Life is thought to be long.

In your examples, they can be switched with some adjustment in the form.

Implication: People thought it would be more difficult than it turned out to be.


意外」 is used when what you're describing is unexpected.

案外」 is used when what you're describing is contrary to what you expected and is most frequently used with adjectives.

「案外安い」 OK
「案外簡単」 OK

However, I don't believe that you can say 「案外に」 the way that you would say 「意外に」

「案外に安い」 NG ⇒ 「意外に安い」 OK
「案外に簡単」 NG ⇒ 「意外に簡単」 OK

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