To provide an engine-driven working machine provided with an automatic control means for engine revolution which enables reduction of worker's load, improvement of working efficiency, fuel economy and safety by automatically controlling the throttle opening to enhance efficiency in response to load fluctuation.

The engine-driven working machine has an engine revolution-control means 100 which is provided with a throttle control motor 8, and a controller 1 for outputting to the motor 8, a control signal for automatically shifting the engine revolution into the range of working threshold when the engine revolution reaching the working revolution fluctuates out of the range of working threshold corresponding to the working revolution.