“〜mono de wa nai・〜mono demo nai”: Shouldn't / Not Necessarily Not [JLPT N1]
Content by NTJ Kuma · Nihongo to Japan editorial team · Updated July 27, 2026
「いじめるものではない」／「できないものでもない」 — a common-sense “don't” vs a hedged “not impossible.”
「人の悪口を言うものではない」 — one shouldn't (by reason), or gently ‘it's not that it isn't…'
To admonish by reason that one “shouldn't do ～,” 「人の悪口を言うものではない」 (one shouldn't speak ill of others) — 「〜ものではない・〜ものでもない」 is a pair of 「もの」 negations: ものではない = shouldn't ～ (by reason／common sense); ものでもない = it's not that it isn't ～, not necessarily not ～ (partial affirmation). This guide separates the two and links them to 「べきではない (shouldn't, by obligation)」 and the affirmative 「ものだ.」
Core: one ‘shouldn't,' one ‘it's not that it isn't…'
This pair uses 「もの」 for two related but different meanings:
① 〜ものではない = shouldn't ～ (admonishing by reason／common sense／norm):
- 食べ物を粗末にするものではない (one shouldn't waste food).
- 人を見た目で判断するものではない (one shouldn't judge by appearance).
② 〜ものでもない = it's not that it isn't ～, not necessarily not ～ (a softened double negative, partial affirmation):
- 練習すれば、できないものでもない (with practice, it's not that it can't be done).
- 彼の意見も、聞いてみればまんざら悪いものでもない (his opinion, once heard, isn't half bad either).
Feel: 「ものではない」 = (by reason) shouldn't ～ — with an admonishing, instructive flavor (often an elder admonishing a junior); 「ものでもない」 = it's not that it isn't ～, not necessarily not ～ — a softened double negative, partial affirmation leaving room (it's not fully ～, but it's not that it isn't ～ either). In English: ものではない = “shouldn't ～”; ものでもない = “it's not that it isn't ～, not necessarily not ～.”
How it attaches
| Form | Meaning | Example |
|---|---|---|
| verb dictionary form ＋ ものではない | shouldn't ～ (admonish by reason) | 言うものではない （that's not the sort of thing you say） |
| verb potential／ない-form ＋ ものでもない | it's not that it isn't ～, not necessarily not ～ | できないものでもない （it's not that it can't be done） |
Examples in use
- そんな乱暴な言葉を使うものではない。(One shouldn't use such rough words.)
- 一人でやれないものでもないが、手伝ってもらえると助かる。(It's not that I can't do it alone, but help would be appreciated.)
- 彼の提案は、検討する価値がないものでもない。(His proposal isn't without worth considering.)
- 年を取るのも、悪いものでもない。(Getting older isn't a bad thing either.)
- 恩人を裏切るものではない。(One shouldn't betray a benefactor.)
⚠️ Common mistakes to avoid
① Two related but different meanings: ものではない (shouldn't ～) vs ものでもない (it's not that it isn't ～). This is the pair's core distinction. One 「も」 apart, the meanings differ greatly. 「〜ものではない」 = shouldn't ～ (admonishing by reason／common sense): it points out from “reason, common sense, social norm” that “(doing) ～ is wrong, improper,” with an admonishing, instructive flavor: 嘘をつくものではない (one shouldn't lie), 恩人を裏切るものではない (one shouldn't betray a benefactor). It's often for “(by reason,) you shouldn't do ～” admonition (especially an elder to a junior). 「〜ものでもない」 = it's not that it isn't ～, not necessarily not ～ (a softened double negative, partial affirmation): it's “(though not fully ～,) it's not that it isn't ～, not necessarily not ～,” a partial affirmation leaving room: できないものでもない (it's not that it can't be done), 悪いものでもない (it's not bad either). Test: to “(by reason) admonish «shouldn't ～»” → ものではない; to “(gently) say «it's not that it isn't ～, not necessarily not ～»” → ものでもない.
② Different attachment: ものではない takes the dictionary form, ものでもない takes the potential／ない-form／adjective. Get the attachment right. 「ものではない」 (admonition) precedes a verb dictionary form: 言うものではない, するものではない (for “shouldn't do ～”). 「ものでもない」 (partial affirmation) precedes a verb potential／ない-form／adjective: できないものでもない (it's not that it can't be done), 悪いものでもない (it's not bad either). Mnemonic: dictionary form ＋ ものではない (shouldn't ～); potential／ない-form／adjective ＋ ものでもない (it's not that it isn't ～).
③ Division of labor with 「べきではない」; ものではない is the negative of 「ものだ.」 「ものではない」 (shouldn't by reason) vs 「べきではない」 (shouldn't by obligation): both mean “shouldn't,” but — 「ものではない」 leans “(by reason, common sense) one just shouldn't ～” (with a universal-reason, admonishing flavor): 人を傷つけるものではない (one shouldn't hurt others — universal reason); 「べきではない」 leans “(by obligation, ought-to) shouldn't ～” (more direct, for a specific situation): 今、それを言うべきではない (you shouldn't say that now — a judgment about this moment). Also, 「ものではない」 is the negative of the affirmative 「ものだ」 — 「ものだ」 means “(by reason) it just ～, ought to ～” (reason／sentiment, see 〈ものだ〉): 困ったときは助け合うものだ (in trouble, people should help each other); its negative 「ものではない」 = “(by reason) shouldn't ～”: 困っている人を見捨てるものではない (one shouldn't abandon someone in trouble). Test: to “(by reason, universally) admonish «shouldn't ～»” → ものではない (see the reason use of 〈ものだ〉); “(by specific obligation) shouldn't ～” → べきではない.
🔄 Nuance & comparison: ものではない／ものでもない／べきではない／ものだ
| Form | Emphasis | Example |
|---|---|---|
| 〜ものではない | shouldn't ～ (admonish by reason／common sense) | 言うものではない （that's not the sort of thing you say） |
| 〜ものでもない | it's not that it isn't ～, not necessarily not ～ (partial affirmation) | できないものでもない （it's not that it can't be done） |
| 〜べきではない | shouldn't ～ (by obligation, more direct) | 言うべきではない （you ought not to say it） |
| 〜ものだ | (by reason) it just ～, ought to ～ (reason／sentiment) | 助け合うものだ |
💡 Quick takeaway
「〜ものではない・〜ものでもない」 — three points: ① two related but different meanings — 「ものではない = shouldn't ～」 (admonishing by reason／common sense, instructive); 「ものでもない = it's not that it isn't ～, not necessarily not ～」 (a softened partial affirmation); ② different attachment — dictionary form ＋ ものではない／potential・ない-form ＋ ものでもない; ③ division of labor with 「べきではない (shouldn't by obligation, more direct)」; 「ものではない」 is the negative of 「ものだ (by reason, see 〈ものだ〉).」 This set's 「ものではない」 has a real “elder's teaching” flavor — 「人の悪口を言うものではない (one shouldn't speak ill of others)」 reasons more gently and measuredly than 「言うな」; while 「ものでもない」 is the softened “it's not that it isn't ～” (leaving room for oneself or the matter). To admonish by reason “shouldn't ～” use ものではない; to gently say “it's not that it isn't ～” use ものでもない.
❓ Quick FAQ
Q: What's the difference between 「言うものではない」 and 「言うべきではない」? Both ‘shouldn't say'?
The difference is ‘(universal) reason／common sense' vs ‘(situation-specific) obligation／ought-to.' 「〜ものではない」 = (by reason, common sense) one just shouldn't ～ (with a universal-reason, admonishing flavor): it points out from “universal reason, common sense, social norm” that “(this kind of thing) one just shouldn't do,” with an instructive, admonishing flavor and a “general-reason” weight, often for an elder teaching a junior: 人の悪口を言うものではない (one shouldn't speak ill of others — a universal principle of conduct), 食べ物を粗末にするものではない (one shouldn't waste food — general upbringing), 恩を仇で返すものではない (one shouldn't return kindness with harm). Its flavor is “(by the principles of conduct,) one just shouldn't do this.” 「〜べきではない」 = (by obligation, ought-to) shouldn't ～ (more direct, for a specific situation): it judges by “whether one should (obligation, ought),” more direct, rational, for a specific situation: 今、その話をするべきではない (you shouldn't bring that up now — a judgment about “this moment”), 感情的になるべきではない (you shouldn't get emotional — advice for a specific situation), 彼を責めるべきではない (you shouldn't blame him — a judgment about this matter). Its flavor is “(judging by this situation,) you shouldn't ～.” Difference: 「ものではない」 leans “(universal reason, common sense) one just shouldn't ～” (an instructive, upbringing flavor); 「べきではない」 leans “(by specific obligation, ought-to) shouldn't ～” (more direct, situation-specific). Test: to say “(by principles of conduct, universally) one shouldn't ～” (instructive) → ものではない; to say “(judging by this situation, obligation) you shouldn't ～” (situation-specific) → べきではない. E.g. 「嘘をつくものではない (one shouldn't lie — a universal moral teaching)」 uses ものではない; 「その場で嘘をつくべきではなかった (you shouldn't have lied then — a judgment about that specific situation)」 uses べきではない. One is “admonition by universal reason,” one is “an ought-to judgment about a specific situation.”
Q: What does 「できないものでもない」 mean? Why is it ‘it's not that it can't be done'?
「〜ものでもない」 = “it's not that it isn't ～, not necessarily not ～,” a softened double negative, partial affirmation. Unpacking: it's the double negative “〜ない (negative) ＋ ものでもない (it's not that either)” — 「できない (can't do)」 ＋ 「ものでもない (it's not that either)」 = “it's not that «can't do»” = “(actually) it's not that it can't be done, it can still be done.” It uses a double negative to express a room-leaving, softened partial affirmation: “(though not easy,) it's not fully impossible, not necessarily not ～.” E.g.: 一人でやれないものでもない (it's not that I can't do it alone — leaving room, implying “with effort it can be done”), 彼の案も、悪いものでもない (his plan isn't bad either — a softened affirmation “it's fairly good”), 努力次第で、不可能というものでもない (depending on effort, it's not necessarily impossible). Its feel is “(without overstating,) it's not that it isn't ～, not necessarily not ～” — more roundabout and room-leaving than bluntly saying 「できる (can do),」 often with a “(though it's hard,) it's still possible” softened affirmation. Test: to gently, with room, say «it's not that it isn't ～, not necessarily not ～» (a partial affirmation via double negative) → 〜ものでもない. It's the opposite of asserting “absolutely not ～” — it's the roundabout affirmation “it's not that it isn't ～ (it's actually possible).” So 「できないものでもない」 = “it's not that it can't be done (it can actually still be done),” a room-leaving, softened phrasing.
🖊️ Practice Quiz
Q1. 「お年寄りには、親切にする___。」(one ought to / a precept)
(A) ものだ (B) ものではない (C) わけがない (D) どころではない
Q2. What does 「言うものではない」 mean?
(A) (by common sense) one shouldn't say it
(B) one must say it
(C) wants to say it
(D) already said it
Q3. What does 「できないものでもない」 mean?
(A) it's not necessarily impossible (a tentative affirmation)
(B) totally impossible
(C) definitely impossible
(D) doesn't want to do it
Q4. What's the nuance of 「ものではない」?
(A) a common-sense precept (one shouldn't do that)
(B) a strong personal assertion
(C) pure time
(D) a wish
Q5. Which connection is correct?
(A) 弱い者をいじめるものではない。
(B) いじめたものではない。
(C) できるものでもない。
(D) 言うものでもない shouldn't.
Answer Key
1. (A) ものだ ── 親切にするものだ = one ought to be kind (common sense). (ものではない is the negative precept ‘shouldn't.')
2. (A) ── (by common sense) one shouldn't say it.
3. (A) ── 〜ものでもない = it's not necessarily impossible (a tentative affirmation).
4. (A) ── a common-sense precept (one shouldn't do that).
5. (A) 弱い者をいじめるものではない ── dict. form ＋ ものではない: you shouldn't bully the weak (correct).