～一方だ — A change that only keeps going one way | JLPT N3 grammar

Meaning

Describes a trend that moves in one direction only and shows no sign of stopping: 'more and more', 'just keeps rising' or 'just keeps falling'. Usually about something unwelcome, but it can be neutral. Not to be confused with 一方で, which contrasts two facts.

Formation

Vる＋一方だ: 増える → 増える一方だ
Aい → Aくなる＋一方だ: 悪い → 悪くなる一方だ
Aな／N → Aに／Nになる＋一方だ: 不便 → 不便になる一方だ
Vる＋一方の＋N (before a noun): たまる → たまる一方のメール
Past and polite: 一方だった／一方です: 落ちる → 落ちる一方だった

When to use it

Where to use it: For ongoing trends — prices, population, workload, health, debt: 物価は上がる一方だ 'prices just keep going up'. Works both in conversation and in the news.
Where not to use it: Not with verbs that don't express change, and not for one-off actions (✗ 毎日食べる一方だ). Not for contrasting two facts — that is 一方で.

Examples

20 sentences

若者わかものが出てでていくので、町まちの人口じんこうは減るへる一方いっぽうだ。
Young people keep moving away, so the town's population just keeps shrinking.
最近さいきん、残業ざんぎょうが増えるふえる一方いっぽうです。
Lately my overtime just keeps piling up.
薬くすりを飲んでものんでも、腰こしの痛みいたみはひどくなる一方いっぽうだ。
Even with medicine, my back pain just keeps getting worse.
駅前えきまえのスーパーがなくなって、町まちは不便にふべんになる一方いっぽうだ。
The supermarket by the station is gone, and the town keeps getting less convenient.
たまる一方いっぽうのメールに、毎朝まいあさうんざりする。
Every morning I'm fed up with the emails that just keep piling up.
あの頃ころ、会社かいしゃの売り上げうりあげは落ちるおちる一方いっぽうだった。
Back then, the company's sales did nothing but fall.
うちの電気代でんきだい、高くたかくなる一方いっぽうだと思わないおもわない？
Don't you think our electricity bill just keeps going up?
海うみの水温すいおんは、年々ねんねん上がるあがる一方いっぽうだそうです。
I hear the sea temperature keeps rising year after year.

12 more examples

口コミくちこみのおかげで、店みせの評判ひょうばんは広がるひろがる一方いっぽうです。
Thanks to word of mouth, the shop's reputation keeps spreading.
地方ちほうでは、高齢化こうれいかが進むすすむ一方いっぽうだ。
In rural areas, the population just keeps getting older.
入院中にゅういんちゅう、祖母そぼの体からだは弱るよわる一方いっぽうだった。
While she was in the hospital, my grandmother just kept getting weaker.
片付けてもかたづけても片付けてもかたづけても、子ども部屋こどもべやは散らかるちらかる一方いっぽうだ。
No matter how much I tidy up, the kids' room just keeps getting messier.
十二月じゅうにがつに入ってはいって、朝あさの冷え込みひえこみは厳しくきびしくなる一方いっぽうです。
Since December began, the morning cold has been getting harsher and harsher.
夜勤やきんが増えてふえて、生活せいかつは不規則にふきそくになる一方いっぽうです。
With more night shifts, my daily routine keeps getting more irregular.
再開発さいかいはつが進んですすんで、この辺りあたりはにぎやかになる一方いっぽうだ。
As the redevelopment moves ahead, this area keeps getting livelier.
膨らむふくらむ一方いっぽうの医療費いりょうひが国くにの大きなおおきな問題もんだいになっている。
Ever-growing medical costs have become a major problem for the country.
なぜ子どもこどもの視力しりょくは下がるさがる一方いっぽうなのでしょうか？
Why does children's eyesight keep getting worse?
カメラを始めてはじめてから、貯金ちょきんは減るへる一方いっぽうです。
Ever since I took up photography, my savings have just kept shrinking.
日本語にほんごを使うつかう機会きかいがなく、会話力かいわりょくは衰えるおとろえる一方いっぽうです。
I have no chance to use Japanese, so my speaking skills just keep getting rustier.
大型おおがたスーパーができて、商店街しょうてんがいの客足きゃくあしは遠のくとおのく一方いっぽうだ。
Since a big supermarket opened, the shopping street has been losing more and more customers.

Important notes

The verb before 一方だ is always in the dictionary form, even about the past; tense goes on the copula at the end (落ちる一方だった).
It is often negative, but unlike ばかりだ it can also be neutral or positive: ファンは増える一方だ.

Common mistakes

✗ 冬になって、寒い一方だ → ✓ 寒くなる一方だ — 一方だ needs a verb of change; turn the adjective into a change with なる.
✗ 売り上げは落ちた一方だった → ✓ 落ちる一方だった — only the dictionary form goes before 一方; the past tense goes at the end.
✗ 人口が減る一方で。 → ✓ 人口が減る一方だ。 — 一方で links two clauses ('while…'); a statement about a trend ends in 一方だ.

Check yourself

Pick the translation of each sentence. The wrong options translate similar patterns, so watch the grammar rather than the words.

Sentence 1: 口コミくちこみのおかげで、店みせの評判ひょうばんは広がるひろがる一方いっぽうです。 The rain won't stop, and the river just keeps rising.AI translation is advancing rapidly, while subtle nuances of a dialect are still hard to convey.Thanks to word of mouth, the shop's reputation keeps spreading.
Sentence 2: 再開発さいかいはつが進んですすんで、この辺りあたりはにぎやかになる一方いっぽうだ。 If things go on like this, your debt will just keep growing.The population is growing in this area, whereas it is declining in the neighboring town.As the redevelopment moves ahead, this area keeps getting livelier.
Sentence 3: 大型おおがたスーパーができて、商店街しょうてんがいの客足きゃくあしは遠のくとおのく一方いっぽうだ。 Cafés are increasing near the station, while small bookstores are disappearing.No matter how many times they talked it over, their relationship only got worse.Since a big supermarket opened, the shopping street has been losing more and more customers.