A mold clamping device includes a base, a stationary platen fixed to the base and supporting a stationary mold, a movable platen movable on the base and supporting a movable mold, and a mold clamping mechanism for clamping the movable mold against the stationary mold. Tie bars extend from the stationary platen completely through both the movable platen and the mold clamping mechanism. A shaft supporting plate is fixed to the ends of the tie bars and terminates at its lower end portion in two spaced-apart shoes that have flat bottom surfaces in direct sliding contact with the base. The flat bottom surface of each shoe has a larger area than the cross-sectional area of the shaft supporting plate situated vertically above the shoe.