Provided is a construction machine capable of more efficiently utilizing the energy of return operating oil from a hydraulic actuator. The present invention is provided with: an engine (11); a hydraulic pump (13) which is driven by the engine (11); a hydraulic actuator (17) which is driven by a fluid discharged from the hydraulic pump (13); a discharge pressure sensor (12d) which detects a discharge pressure from the hydraulic pump (13); a hydraulic regenerative motor (18) which is driven by return operating oil from the hydraulic actuator (17); a flow meter (18e) which detects the flow rate of the return operating oil; a flow dividing valve (50) which controls the rate of inflow to the hydraulic regenerative motor (18); a controller (15) which controls the flow dividing valve (50) according to the discharge pressure detected by the discharge pressure sensor (12d) and the flow rate detected by the flow meter (18e); a regenerative electric generator (19) which generates electric power by being driven by the power of the hydraulic regenerative motor (18); and an electric-powered electric generator (13) which assists the drive of the engine (11) by the electric power supplied from the regenerative electric generator (19).