PROBLEM TO BE SOLVED: To enable good movement urging of a detection operation unit by a torsion spring for a long period of time. SOLUTION: A speed change lever 33 that can operate a speed change device for traveling and can be operated from a travel neutral position 56a of a travel speed change operation path to an engine stop position 65, and moves with the operation of the speed change lever 33. Control to stop the engine based on the detection operation unit 66, the position detection sensor on which the detection operation unit 66 operates when the shift lever 33 is operated to the engine stop position 65, and the detection operation of the position detection sensor. A torsion spring 68 that is provided with means and moves and urges the detection operation unit 66 is provided at one end, and a first winding support portion 68a that is wound around a shaft portion 69 provided in the detection operation unit 66 is provided. The other end is provided with a second winding support portion 68b that is wound around a fixing pin 70 provided on the fixing portion on the machine body side, and is spirally provided between one end and the other end. A winding portion 68c is provided. [Selection diagram] FIG. 14【課題】捩りバネによる検知用操作部の移動付勢を長期にわたって良好に行えるようにすることが要望されていた。【解決手段】走行用の変速装置を操作可能であり、且つ、走行変速用操作経路の走行中立位置５６ａからエンジン停止位置６５に操作可能な変速レバー３３と、変速レバー３３の操作に伴って移動する検知用操作部６６と、変速レバー３３がエンジン停止位置６５に操作されるに伴って検知用操作部６６が作用する位置検出センサと、位置検出センサの検出作動に基づいてエンジンを停止させる制御手段とが備えられ、検知用操作部６６を移動付勢する捩りバネ６８が、一端部に、検知用操作部６６に備えられた軸部６９に巻回される第１巻回支持部６８ａが備えられ、他端部に、機体側の固定部に設けられた固定ピン７０に巻回される第２巻回支持部６８ｂが備えられ、且つ、一端部と他端部との間に螺旋状巻回部６８ｃが備えられている。【選択図】図１４
