“〜naze ka to iu to・〜to iu no mo”: The Reason Is (conclusion first, then reason) [JLPT N2]

Content by NTJ Kuma · Nihongo to Japan editorial team · Updated July 27, 2026

「彼は来なかった。なぜかというと…」 — drop the conclusion first, then circle back to the reason.

「今日は早く帰る。なぜかというと…」 — drop the conclusion first, then self-answer the reason

「今日は早く帰るよ。なぜかというと、明日試験だから」 (I'm heading home early today. If you ask why, it's because I have an exam tomorrow) — 「〜なぜかというと・〜というのも」 = the reason being…, used to state the conclusion first, then turn back to explain the cause. They're the same family as the more written connector 「なぜなら」, but more colloquial, with an “adding an explanation” flavor. This guide covers their use, the sentence-end echo, and their division of labor with 〈なぜなら〉.

Core: conclusion first, cause added after (self-Q&A／explanatory)

Both express “state the result or claim first, then go on to explain the cause,” with slightly different flavors:

• なぜかというと = if you ask why, it's because… (self-Q&A): like asking “why?” on the listener's behalf and answering it yourself — colloquial, friendly. Often ends with 「〜からだ／〜んだ.」
• というのも = that's because…, actually it's because… (adding background): taking up the previous clause and adding a background cause, often with the explanatory sense of “(I say/do this) actually because….” Often ends with 「〜からだ.」

Feel: “(if you ask) why, it's because…／that's because…” — the core is result-first, cause-after, turning back to explain, more colloquial than 「なぜなら」, more like adding an explanation mid-conversation.

Attachment rules

Examples in context

• 私はその案に反対だ。なぜかというと、リスクが大きすぎるからだ。(I oppose that plan. If you ask why, it's because the risk is too great.)
• 彼に連絡した。というのも、急な変更があったからだ。(I contacted him. That's because there was a sudden change.)
• 今日は外食にしよう。なぜかというと、冷蔵庫が空だから。(Let's eat out today. If you ask why, the fridge is empty.)
• 少し驚いた。というのも、彼が現れるとは思わなかったからだ。(I was a bit surprised. That's because I didn't think he'd show up.)
• 早めに家を出た。なぜかというと、道が混むと思ったからだ。(I left home early. If you ask why, it's because I thought the roads would be jammed.)

⚠️ Common mistakes to avoid

① The end must echo with 「〜からだ／〜のだ」; don't drop it. After 「なぜかというと」「というのも」 opens the cause, the sentence end almost always must close with 「〜からだ／〜からです／〜のだ」 (because of the fact that…). なぜかというと、疲れたからだ (○) / なぜかというと、疲れた (△, missing からだ feels incomplete). This 「からだ」 echoes the earlier “(why),” forming the complete Q&A structure “why? — because ….” The Chinese “之所以…是因為…”'s “是因為” corresponds to this sentence-final 「からだ.」 When writing, remember to pair head and tail: なぜかというと〜からだ.

② 「なぜかというと」 is colloquial self-Q&A; formal essays use 「なぜなら」. 「なぜかというと」 has a clear colloquial, conversational color, like asking “why?” on the other's behalf and answering it, suited to speech, casual writing, blogs. For formal essays, reports, academic writing, “that's because” more often uses the written 「なぜなら（ば）」 (see 〈なぜなら〉). Test: conversation, colloquial, essays → なぜかというと; papers, formal reports → なぜなら. Writing 「なぜかというと」 in a formal paper sounds too casual.

③ 「というのも」 carries an ‘actually it's because' background flavor, slightly unlike 「なぜかというと」. Both are result-first, cause-after, but 「というのも」 is more often used to add a ‘behind-the-scenes cause, hidden reason' to one's own preceding words/act, with the explanatory sense of “(the reason I did this) is actually because…”: 断った。というのも、体調が悪かったからだ (I declined. Actually because I wasn't feeling well). It often follows an act or emotion that needs explaining, supplying the reason. 「なぜかというと」 more neutrally self-Q&As “if you ask why.” Finer: to “add a hidden reason/background” use というのも; to plainly “explain the reason self-Q&A style” use なぜかというと. The two are often interchangeable, but というのも has a stronger “actually” flavor.

🔄 Compare: なぜかというと／というのも／なぜなら／〜から

💡 Learning tip

「なぜかというと」「というのも」 are both ways of stating the conclusion first, then turning back to add the cause — three points: ① pair head and tail — the opening 「なぜかというと／というのも」 must have the sentence end echo with 「〜からだ／〜のだ」 (the reason … is because …), don't drop it; ② register division — 「なぜかというと」 is colloquial self-Q&A (for conversation, essays), while formal essays use the written 〈なぜなら〉; ③ というのも carries an ‘actually it's because' background flavor, often used to supply a hidden reason for an act/emotion, one layer more “explanatory” than 「なぜかというと.」 All three are “result-first, cause-after,” differing in register and flavor: colloquial self-Q&A = なぜかというと, adding background = というのも, written argument = 〈なぜなら〉. In everyday speech, to “state the point first, then explain,” the structure 「〜。なぜかというと、〜からだ」 is very handy.

❓ Common questions

Q: 「なぜかというと」 and 「なぜなら」 both mean ‘that's because' — what's the difference?

Nearly the same meaning (both state the conclusion first, then add the cause); the difference is mainly register (colloquial vs written). 「なぜかというと」 = if you ask why, it's because… (colloquial, self-Q&A): it carries a self-Q&A frame of “(if asked) why,” like posing the listener's question and answering it, with a friendly, colloquial tone, suited to speech, conversation, casual writing, blogs: 私は行かない。なぜかというと、疲れているからだ (I'm not going. If you ask why, it's because I'm tired). 「なぜなら（ば）」 = that's because (connector, written/formal): it's a formal connector that brings out the cause with a straight “that's because,” without the self-Q&A tone, with a formal, written register — the first choice for essays, reports, academic writing: この政策には反対である。なぜなら、財政負担が大きいからだ (I oppose this policy. That's because the fiscal burden is large). Both echo with 「〜からだ」 at the end. Test: colloquial, conversation, essays → なぜかというと; papers, formal reports, written argument → なぜなら (see 〈なぜなら〉). In short, 「なぜかというと」 is the colloquial version of 「なぜなら」 — same meaning, just different setting and tone.

Q: Are 「というのも」 and 「なぜかというと」 interchangeable?

In most cases yes (both result-first, cause-after, ending with からだ), but the feel differs slightly. 「なぜかというと」 = if you ask why (neutral self-Q&A): purely “(if you ask why) it's because…,” adding a reason to the preceding conclusion, neutral in tone. 「というのも」 = that's because, actually because (adding background/hidden reason): it's more often used to supply the behind-the-scenes cause or hidden reason for one's own preceding ‘act, emotion, or oddity,' with the explanatory flavor of “(the reason I'm like this) is actually because…”: 急に黙り込んだ。というのも、その話題が辛かったからだ (he suddenly fell silent. That's because the topic was painful for him). 「というのも」 is natural here, explaining the hidden reason behind an oddity that needs explaining. Switching to 「なぜかというと」 also works, but loses that “there's actually a hidden reason” flavor. Finer: plain self-Q&A adding a reason → なぜかというと; supplying a ‘hidden reason, background' for an act/emotion → というのも (stronger “actually” flavor). In practice the two are often swappable; just remember 「というのも」 leans “adding background/hidden reason” and 「なぜかというと」 leans “neutral self-Q&A.”

🖊️ Practice Questions (5)

Q1. 「彼は来なかった。___、急用ができたからだ。」(the reason being)

(A) なぜかというと　(B) それなのに　(C) ところが　(D) それでも

Q2. 「なぜかというと」の後句の結尾は?

(A) 〜からだ／〜のだ

(B) 〜ください

(C) 〜なさい

(D) 〜ましょう

Q3. 「というのも〜からだ」の働きは?

(A) Adds an explanation of the aforementioned reason (this is because)

(B) Indicates concession

(C) Indicates condition

(D) Indicates purpose

Q4. この表現の語順は?

(A) State the conclusion first, then add the reason

(B) State the reason first, then the conclusion

(C) Only the reason

(D) Only the conclusion

Q5. 用法が自然なのは?

(A) 反対だ。なぜかというと、危険だからだ。　(B) なぜかというと行く。

(C) というのも、それは美しい(理由なし)。　(D) なぜかというとだ高い。

Answer Explanations

1. (A) なぜかというと ── the reason he didn't come is that he had an urgent matter.

2. (A) ── the second clause often ends with からだ/のだ.

3. (A) ── adds an explanation of the reason.

4. (A) ── conclusion first, then the reason.

5. (A) ── 「なぜかというと〜からだ」 is correct.