You've learned the four big conditionals: ば, たら, と, and なら. You might think you've covered all the ways to say "if." But Japanese has one more conditional hiding in plain sight — ては (では) — and it specializes in bad outcomes.
The Core of ては: Negative Consequences
ては means "if things are like this... (the result will be bad)":
| Example | Meaning |
|---|---|
| このままでは会社はつぶれるだろう。 | If things stay like this, the company will go under. |
| こんなに寒くては体が持たないだろう。 | If it's this cold, your body won't hold up. |
| そんなに食べては太るよ。 | If you eat that much, you'll get fat. |
Notice: the clause after ては is almost always a negative outcome — bankruptcy, physical breakdown, weight gain. This is what sets it apart from other conditionals.
Conjugation Rules
| Word type | ては form | Example |
|---|---|---|
| Verb | て-form + は | 食べては太る |
| い-adjective | く + ては | 寒くては持たない |
| な-adjective | では | 不便では困る |
| Noun | では | このままではダメだ |
な-adjectives and nouns use では, which is simply で + は. Verbs and い-adjectives use ては.
Casual Contractions: ちゃ & じゃ
In spoken Japanese, ては contracts to ちゃ, and では contracts to じゃ:
| Written | Spoken | Meaning |
|---|---|---|
| 食べては太る | 食べちゃ太る | You'll gain weight if you eat that |
| このままではダメだ | このままじゃダメだ | This won't do as is |
The Prohibition Pattern: てはいけない
The most common use of ては is a pattern you've likely already learned — prohibition:
食べてはいけません。 You must not eat (that).
The logic behind this pattern:
- 食べては = if you eat it
- いけない = it won't do / it's no good
Together: "If you eat it, that won't do" = "You must not eat it."
| Prohibition | Breakdown |
|---|---|
| ここで写真を撮ってはいけません。 | If you take photos here → no good |
| 遅刻してはいけない。 | If you're late → no good |
| 授業中に携帯を使ってはなりません。 | If you use your phone in class → no good |
てはいけない and てはならない mean the same thing. The latter is more formal.
ては vs Other Conditionals
| ては | たら | と | |
|---|---|---|---|
| Back clause | Negative only | Anything | No volition |
| Nuance | Warning/worry | Neutral | Objective/habitual |
| Casual form | ちゃ/じゃ | — | — |
Compare these two:
| たら (neutral) | ては (negative) |
|---|---|
| 甘いものを食べたら、歯を磨いてね。 | 甘いものを食べては太るよ。 |
| If you eat sweets, brush your teeth. | If you keep eating sweets, you'll get fat. |
たら simply states a condition and result with no judgment. ては carries a tone of warning — "this is bad for you."
The Repetition Pattern
ては can also express repeated alternation between two actions:
| Example | Meaning |
|---|---|
| 書いては消し、書いては消した。 | Wrote and erased, wrote and erased. |
| 食べては寝、食べては寝の生活。 | A life of eating then sleeping, eating then sleeping. |
The structure is V1ては V2, V1ては V2 — two actions cycling endlessly.
Summary
- ては/では = "if things continue like this (bad outcome)" — the back clause is always negative
- Conjugation: verb て-form + は, い-adj く + ては, な-adj/noun + では
- Casual contractions: ては → ちゃ, では → じゃ
- てはいけない = "if you do it → no good" = prohibition
- Also expresses repetition: 書いては消し = wrote and erased over and over
Self-Check
Q1. Can you replace では with たら in 「このままでは会社はつぶれるだろう」?
Show answer
Grammatically, you could say 「このままだったら会社はつぶれるだろう」, but the nuance changes. では carries a warning tone — "if this keeps up, we're in trouble." たら is more neutral and matter-of-fact.
Q2. Why does 「食べてはいけません」 use ては instead of たら?
Show answer
Because the prohibition pattern is a fixed expression using ては. 「てはいけない」 literally means "if you do it, it won't do." You cannot say 「食べたらいけません」 in standard Japanese (though Kansai dialect has a similar form).
Q3. Convert 「このままじゃダメだ」 back to its written form.
Show answer
このままではダメだ。 じゃ is the casual contraction of では.