To utilize engine speed command signal corresponding to an electronic governor commonly by a mechanical governor.

An accelerator dial 31 is operated for setting engine speed. A main controller 32 outputs an engine speed command signal according to a set value input from the accelerator dial 31. An accelerator actuator 33 actuates a mechanical governor 35 of a diesel engine 34 according to the engine speed command signal. The accelerator actuator 33 has a driver circuit 41 which outputs a driving signal upon receiving the engine speed command signal for enabling controlling of an electronic governor 37 of another diesel engine 36, a governor driving mechanism 42 for driving the mechanical governor driven based on the driving signal from the driver circuit 41, and a potentiometer 43 which senses operation rate of the governor driving mechanism 42 and feeds it back to the driver circuit 41.