～ていく (2) (ongoing change)

Japanese Grammar Basic Japanese ★★★★ 4/5 neutral いくiku
読み いく
ローマ字 iku
形 Verb て-form + いく/いきます
漢字の分解 行 (こう/い.く) — go, carry out

意味

An auxiliary verb construction where いく follows the て form of a verb to express that an action or state continues to change or progress from the present into the future. It describes a gradual, ongoing shift moving forward in time.

This temporal use of ていく expresses that a change or trend will continue developing from now onward. The speaker observes a current state and projects that the change will keep going into the future. Common examples include populations decreasing, technology advancing, or seasons changing. This contrasts with てくる in its temporal sense, which describes changes that have been progressing up to the present moment. ていく looks forward; てくる looks back. The pattern works with both change-of-state verbs (増える, 減る, 変わる) and action verbs viewed as ongoing processes. Learners sometimes struggle to distinguish the directional and temporal uses; context usually makes it clear — if no physical movement is involved, the temporal reading applies.

例文

  1. これから気温が下がっていくでしょう。
  2. 日本語を続けて勉強していくつもりです。
  3. この町の人口は減っていくだろう。

使い方ガイド

場面: spoken, written, everyday

トーン: reflective

正しい言い方

  • これからも日本語を頑張っていきます。
  • 環境問題はますます深刻になっていくだろう。
  • 少しずつ慣れていくと思います。

避ける言い方

  • だんだん暖かくなってきた。(Using てくる when describing a future-oriented trend — てくる looks backward to the present, not forward) → これからだんだん暖かくなっていくだろう。
  • 最近物価が上がっていく。(Using ていく for a change already observed up to now — use てきた for past-to-present change) → 最近物価が上がってきた。

起源と歴史

The temporal extension of いく derives from its core meaning of forward movement. The metaphorical mapping from physical space to time — 'going forward' meaning 'continuing into the future' — is a natural semantic development shared by many languages.

文化的背景

世代: All ages

社会的背景: Universal

関連フレーズ

～て (て form) The て form is one of the most versatile verb and adjective conjugations in Japanese. It connects clauses, forms compound verbs, makes requests, and serves as the base for many auxiliary constructions such as ている, てしまう, and ておく. ～てくる (1) (directional) An auxiliary verb construction where くる follows the て form to express that someone or something moves toward the speaker. It indicates physical movement in the direction of the speaker's location. ～てみる (try doing) An auxiliary verb construction where みる follows the て form to express trying or attempting an action to see what happens or what it is like. It conveys the nuance of doing something experimentally or for the first time. ～ことができる (able to) A construction expressing ability or possibility. It states that doing a particular action is possible, either because of personal skill, circumstances, or permission. It is the formal equivalent of the potential form of verbs. ～すぎる (too much) An auxiliary verb attached to verb stems and adjective stems to express that something is done excessively or a state is excessive. It conveys the meaning of 'too much' or 'overly.' ～ていく (1) (moving away) An auxiliary verb construction where いく follows the て form of a verb to indicate that an action or movement proceeds in a direction away from the speaker or a reference point. It describes going somewhere while doing something, or doing something and then going. ～ておく (in advance) An auxiliary verb attached to the て form indicating that an action is done in advance, in preparation for a future need or situation. It conveys the idea of doing something ahead of time and leaving the result in place. ～てくる (2) (emerging change) An auxiliary verb construction where くる follows the て form to express that a process or change has begun and progressed up to the present moment. It describes an emerging or continuing change observed from the speaker's current perspective.
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