The mold clamping device is provided with a first platen to which a stationary mold is attached. A movable mold unit is capable of approaching and moving away from the stationary mold. A second platen is linked to the first platen via a tie bar. When the movable mold unit and the stationary mold are closed, a wedge member is driven onto the movable mold unit to generate mold clamping force. The second platen has a pressure receiving surface. The pressure receiving surface receives, through the wedge member, mold opening force that is generated by filling, with a molding material, the stationary mold and the movable mold unit that are in the closed state.