All the information I try to find on dearu grammar rules, I only manage to find forum answers that it's a formal, written replacement of desu/da.

However sentences like "私の責任{せきにん}であることは承知{しょうち}します。" where it's used in the middle of sentences clearly don't allow for a desu/da to be inserted haphazardly. I could see that people would want to use dearu beyond formality so as to use the sentence structure to fit in more details into one sentence instead of ending it with "私の責任です。承知します。"?

What are the grammar rules for dearu besides the obvious replacement for desu/da that clearly does not encompass nearly everything function of dearu

  • Even though you're writing dearu, keep in mind that de aru is actually two words.
    – user1478
    Feb 8, 2020 at 16:46

4 Answers 4


…on dearu grammar rules, I only manage to find forum answers that it's a formal, written replacement of desu/da.

Indeed, as you mentioned, である can replace だ/です for formality; notably in literature. This much is true.

…where it's used, in the middle of [a sentence], clearly [doesn't] allow for …desu/da to be inserted haphazardly.

Correct, that's an important observation. In the famous book A Dictionary of Intermediate Japanese Grammar, they explain that である can also be used as a "prenominal form" in the middle of sentences, whilst だ and です cannot.

This raises the question: "What is a prenominal form?"

It means である must precede a noun and somehow connect a description to it. It's like the formal version of the 「の」 particle, which incidentally is interchangeable with である in many such cases.

In your example, である has effectively replaced the 「の」 particle to make the sentence more formal.

I've included a reference with the page number for your further reading. I know you asked this question a year ago, but the answer I found is quite different to the answers that already exist here, so I hope this helps!

Reference: Makino, Seiichi; Tsutsui, Michio (1995). A Dictionary of Intermediate Japanese Grammar (50 ed.). Tokyo, Japan: The Japan Times. p. 33. ISBN 978-47-89007-75-7.

  • One minor quibble -- while である is the required form of だ when modifying another noun or noun phrase, である doesn't have to precede a noun: this can be used predicatively, to close a sentence, albeit resulting in a formal and somewhat stilted sound: 犬【いぬ】​**である** ("it is a dog"). Apr 30, 2021 at 18:16
  • Respectfully, I think that was heavily implied to be already understood in both the person's original question, and in the first sentence of my answer. I believe the main purpose of the original question was to inquire on an explanation for 「である」 in the middle of a sentence, since there seems to be a lack of resources on this nuance. May 1, 2021 at 9:16

Your understanding of dearu is correct. I think the point that makes it confusing for you here is koto. The word represents something like the fact that or the matter that in English, and you can have a complete single sentence before it.

There are some varieties in the use of koto, so how about digging into it and learn this useful word? I think this column is explaining it well.


This question seems rather open-ended to me.

Subordinate clauses you mentioned. Another common use of de aru is in negating adjectives:


However sentences like "watashi no sekinin de aru koto ha shouchishiteimasu" where it's used in the middle of words clearly don't allow for a desu/da to be inserted haphazardly.

I'm not so sure about that, you can easily modify that to "Watashi no sekinin da to iu koto wa shouchi shite imasu".


I think it must be pointed out, that lack of spaces in the Japanese language is causing some confusion here.

The use of である that you quote here


is not one suffix word である as in 吾輩は猫である。

わたし の せきにん で ある こと は しょうち します

Break it down and you see what's happening here. The "で" here is the same as the "で" in:

今日 で 春休み は おわり です。

So, don't smush the で and ある together and try to make sense of it as である.

  • I don't think this is really correct. This usage is not the particle で with the verb ある, as that would make no sense ("the case that (something) exists with/using my responsibility"?). This actually is the verb である (a form of だ/です). As others explained, である is being used in place of だ here because だ cannot be used prenominally. This is essentially saying "the case that (こと) it is my responsibility (私の責任である). It's a bit of a stylistic thing in this case, but the same construction can be more clear/significant in other cases like 先生である人 ("a/the person who is a teacher"), etc.
    – Foogod
    May 5, 2021 at 1:04

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