A predetermined speed control pattern B is sct. In a mold clamping process, in a mold closing section Zm, mold closing control is performed at a mold closing speed Vm, and based on a current mold closing speed Vd and a current mold closing position Xd, which are both detected, a deceleration starting position Xmc of the deceleration section Zmd, where the current mold closing speed Vd becomes a zero (O) at a virtual stop position Xc, is sequentially forecasted at each predetermined time interval by calculation. Upon reaching the deceleration starting position Xmc the deceleration section Zmd is started, and in the deceleration section Zmd, based on the detected current mold closing position Xd, a speed command value Dm corresponding to the speed control pattern B is obtained sequentially by calculation, and according to the speed command value Dm deceleration control is performed. Upon reaching a mold clamping-transition speed Vc, a predetermined mold clamping processing is performed via a low-pressure low-speed section Zc.