To reduce engine noise by driving a hydraulic pump properly even if generated horsepower is low for suppressing the rotational speed of an engine in a hydraulic working vehicle which drives a vehicle mechanically by engine power and absorbs a part of engine power taken out by a power take off device PTO so that the hydraulic pump may discharge pressure oil.

This vehicle is provided with a generator 8 which can conduct switching between a generating action which stores electric energy generated according a torque transmission from a hydraulic pump 2 in a storage means 10 and a motor action which transmits torque to the hydraulic pump 2 by receiving the electric energy stored in the storage means 10. With the power of a time-average value of required absorbed horsepower of the hydraulic pump 2 generated at the time of hydraulic operation, this device conducts control so that the generator 8 may be switched to the motor action if the required absorbed horsepower exceeds the time-average value and to the generating action if it does not.