When constructing an injection molding machine M that is equipped with hydraulic pumps 2, which control discharge flow rates by variably controlling the number of revolutions of a drive motor 3, and that drives hydraulic actuators 4a . . . by these hydraulic pumps 2; the injection molding machine M is equipped with a hydraulic drive member 6 having multiple hydraulic pumps 2p and 2q, and a hydraulic oil supply circuit 5 jointly or individually supplying hydraulic oil to be discharged from multiple hydraulic pumps 2p and 2q to a hydraulic actuator 4a, 4b, 4c, 4d or 4e selected from the multiple hydraulic actuators 4a . . . .