〜一方だ

〜一方だ (いっぽうだ) describes a change that moves in exactly one direction, without turning back: 人口は減る一方だ (the population just keeps shrinking). The preceding verb must be a verb of change such as 増える, 減る, 上がる, 悪くなる.

The pattern's characteristic nuance is worry: most 〜一方だ sentences are about a bad trend that keeps going with no sign of stopping — prices rising, an illness worsening, the environment deteriorating. It often appears in writing and news reports.

Compared with 〜つつある, which also describes a change in progress: つつある is neutral and implies gradually approaching a result, while 一方だ emphasizes that the trend just keeps on going with NO stopping point. Be careful not to confuse it with 〜一方で (on the one hand… on the other…) — same kanji, but a completely different contrastive pattern that you'll study separately.

Examples

• この町(まち)の人口(じんこう)は減(へ)る一方(いっぽう)だ。

  The population of this town just keeps shrinking.

• 最近(さいきん)、物価(ぶっか)は上(あ)がる一方(いっぽう)です。

  Lately, prices just keep going up.

• 祖父(そふ)の病気(びょうき)は悪(わる)くなる一方(いっぽう)だった。

  My grandfather's illness just kept getting worse.

Related patterns

• 〜つつある
• （その）一方（で）
• 〜ば〜ほど