Provided is a working machine capable of regenerating and utilizing surplus energy. The working machine related to the present invention is provided with a branching flow path (150) through which hydraulic oil flows between a hydraulic actuator (24) and a hydraulic pump-motor (14), an accumulator (30) arranged in the branching flow path, a first opening/closing valve (31) arranged between the accumulator and the hydraulic pump-motor, and a second opening/closing valve (32) arranged between the accumulator and the hydraulic actuator. A control device (41) selectively introduces the hydraulic oil from the hydraulic actuator and the hydraulic oil from the hydraulic pump-motor to the accumulator and accumulates the same by controlling opening/closing of the first opening/closing valve and the second opening/closing valve.