PROBLEM TO BE SOLVED: To improve usability in a walking lawn mower adopting a dog clutch structure in a transmission.SOLUTION: A walking lawn mower is configured as follows: a biasing member 26 for biasing these halves in a direction to move away from each other in the rotating axis direction of the dog clutch 23 is interposed between an input side half 23a and an output side half 23b constituting a dog clutch 23； the dog clutch is turned on by the power of a driving source when the driving source (engine 14) is rotated forward； and the dog clutch is turned off by the biasing force of the biasing member 16 when the driving force of the driving source is not transmitted to the input side half 23a.SELECTED DRAWING: Figure 2【課題】トランスミッション内にドグクラッチ構造を採用した歩行型芝刈機において、使い勝手の向上をはかる。【解決手段】噛合いクラッチ２３を構成する入力側半体２３ａと出力側半体２３ｂとの間に、これらの半体同士を噛合いクラッチ２３の回転軸方向へ互いに離反させる方向に付勢する付勢部材２６を介在させ、駆動源（エンジン１４）が正回転したときには、駆動源の動力によって噛合いクラッチをオンにし、駆動源の駆動力が入力側半体２３ａへ伝達されないときに付勢部材１６の付勢力によって噛合いクラッチをオフにする構成とした。【選択図】図２
