Abstract: A self-propelled working machine has a pair of transporting parts, a working part, an engine for driving at least the working part, and a main switch for turning the engine on and off. A locomotion preparation switch produces a command for moving the transporting parts when turned on and produces a stop command for stopping movement of the transporting parts when turned off. A locomotion speed setting member orders a target locomotion speed of the transporting parts. A work switch switches the working part on and off. A control part stops the engine when a first condition that the main switch is on, a second condition that the locomotion preparation switch is off, a third condition that the transporting parts have stopped moving and the target locomotion speed ordered by the locomotion speed setting member is zero, and a fourth condition that the work switch is off, are satisfied.