A walk-behind working machine includes a first clutch lever (25), a second clutch lever (22), and a throttle (33) having a degree of opening controllable by each of the first clutch lever and the second clutch lever. The working machine also includes a pivoting member (52), a throttle wire (51) connected to the pivoting member, and a first activating member (62) provided to the first clutch leverfor engagement with an engagement member (56) provided to the pivoting member. When the first clutch lever is operated to place a first clutch (34) in a connected state, the throttle is shifted by operation of the first clutch lever from a first opened position in which an idling engine speed is produced to a second opened position in which a working-machine-activating engine speed is produced.