There is provided a mold clamping apparatus which has a space-saving apparatus construction and can easily carry out mold replacement. The mold clamping apparatus includes: a base; a fixed die plate, fixed on the base, for mounting a fixed mold thereto; a movable die plate, disposed opposite the fixed die plate and movably on the base, for mounting a movable mold thereto; a mold opening/closing means for moving the movable die plate closer to and away from the fixed die plate; a plurality of mold clamping cylinders provided in the fixed die plate; mold clamping pistons fit in the mold clamping cylinders; a plurality of tie bars, each detachably mountable at one end to each mold clamping piston and penetrating the movable die plate and extending; a coupling means for releasably coupling each tie bar to the movable die plate at a position as determined depending on the sum of the thickness of the fixed mold and the thickness of the movable mold; and a tie bar retreating means which, when the movable die plate is in a backward position to form a space for mold replacement operation, moves at least one of the plurality of tie bars, which obstructs the mold replacement operation, backward to a retreat position.
