An injection molding machine for bimaterial molding equipped with two sets of injection units (11,12) capable of plasticization and injection filling of different resin materials, respectively, which injection molding machine comprises, as mold clamping means, hydraulic mold clamping means for simultaneously clamping three sets of die plates (2,3,9); as movable die plate opening/closing means (14), movable die plate opening/closing means driven by an electric motor; as rotary die plate opening/closing means (15), rotary die plate opening/closing means (14) driven by an electric motor; and, asrotating means for a rotary die plate (9), rotational driving means driven by an electric motor mounted on a reversal pedestal (7).