There is provided an engine working machine capable of suppressing functional disorder of an exhaust catalyst and decline of engine performance. If, during input of a dummy load to an engine, fuel supply volume of a fuel supply device reaches a predetermined dummy load cutoff determination value as a result of elevation of a total load for an engine including the dummy load and a work load, then an electronic control device switches a load switching device to cut off the dummy load; and if, during input of the work load without including the dummy load to the engine, the fuel supply volume of the fuel supply device reaches a predetermined dummy load re-input determination value as a result of decline of the work load, then the electronic control device switches the load switching device to re-input the dummy load.