Provided is a working machine including an upper slewing body, a hydraulic motor, a slewing electric motor, a hydraulic pump, a slewing operation device, a control valve, a communication valve having an open position for bringing a motor outlet-side line into direct communication with a tank or a motor inlet-side line, bypassing the control valve, and a close position for blocking the communication, and a control device which performs (i) determining, as a target value, a pressure generated in the hydraulic motor without the communication valve, or a torque obtained from the pressure, based on an operation state and a slewing state, (ii) determining, as an actual value, a pressure actually generated in the hydraulic motor or a torque obtained from the pressure, and (iii) outputting a torque command based on a value obtained by subtracting the actual value from the target value.