Abstract: The present intention intends to operate an ejector which carries out gate cut and product ejection in an injection molding machine, at optimal speeds, respectively. According to the present invention, a control unit for controlling hydraulic or electric drive means for operating one or more than one ejector pin comprises operation speed setting means for gate cut and another operation speed setting means for product ejection. Such a structure enables to carry out gate cut by operating an ejector unit controlled by an ejector unit operation speed setting means for a gate cut and, subsequently, to carry out a product ejection from metallic molds by operating the ejector unit controlled by another ejector unit operation speed setting means for product ejection. The ejector unit is set at a comparatively high operation speed for gate cut so that no gate trace will remain, and at a comparatively low operation speed for product ejection so that no cracks will be generated in the product.