のも当然だ
It is only natural that, It is no wonder
Structure
［い］Adjective + のは(1) + 当然だ
［な］Adjective + な(1) + のは + 当然だ
Noun + は(2) + 当然だ
(1) のも
(2) も
Explanation
Similar to て当然だ, which conveys that something is 'only right' or 'to be expected', the grammar point のは当然だ functions in much the same way. It emphasizes that a certain outcome is 'no surprise' or 'perfectly logical' given the circumstances.
This grammar pattern is attached to the plain form of verbs and い-Adjectives, or to な-Adjectives and nouns that are followed by な.
- 毎日一生懸命練習したから、試合に勝ったのは当然だ。They practiced their hearts out every day, so it's only natural that they won the match.
- 唐辛子をたくさん入れたから、このカレーが辛いのは当然です。I put a lot of chili peppers in it, so of course this curry is spicy.
- 毎日掃除しているから、彼の部屋がきれいなのも当然だ。He cleans every day, so it's no wonder his room is so tidy.
- 昨夜ゲームばかりしていて、試験に不合格も当然だ。I was just playing video games all last night, so it makes sense that I failed the exam.
As shown in a few of the sentences above, も can be used in place of は. This introduces a subtle nuance, with も adding a feeling that this outcome, too, is an obvious or expected part of the situation.
When compared with て当然だ, the のは当然だ form carries a slightly more emphatic tone. It creates a clearer separation between the preceding clause (the reason) and what the speaker deems to be the logical result. The difference is similar to 'winning is expected' versus 'it is expected that you will win' in English.
Examples
全然勉強しなかったんだから、試験に落ちるのも当然だ。
Since you didn't study at all, it's only natural that you would fail the exam.
大切なペットを失ったのだから、悲しいのも当然だ。
Since she lost her beloved pet, it's only natural that she is sad.
あんなにケーキを食べたら、お腹が痛くなるのも当然だよ。
If you eat that much cake, it's only natural that you'd get a stomachache.
田中先生はとても親切だから、学生に人気があるのも当然だ。
Mr. Tanaka is very kind, so it's only natural that he is popular with the students.
何年も使っていれば、パソコンが古くなるのも当然でしょう。
If you use a computer for many years, it's only natural that it would get old.
毎日残業していたのだから、疲れているのは当然だ。
Since he was working overtime every day, it's only natural that he is tired.
大雨が降ったのだから、川が増水するのも当然だ。
Since it rained so heavily, it's only natural that the river's water level would rise.
彼女はプロのシェフだから、おいしい料理が作れるのも当然です。
She's a professional chef, so it's only natural that she can make delicious food.
自分から秘密を話したんだから、みんなに知られるのも当然だよ。
You're the one who told the secret, so it's only natural that everyone knows now.
彼はいつも嘘ばかりついているから、誰からも信用されないのも当然だ。
He is always telling lies, so it's only natural that nobody trusts him.
一晩中寝ていないのだから、眠いのは当然だ。
Since (I) haven't slept all night, it is only natural that (I) am sleepy.
あのレストランは有名だから、いつも混んでいるのも当然ですね。
That restaurant is famous, so it's only natural that it is always crowded.