A predetermined speed control pattern A is set. In controlling mold opening, in the mold opening section Zm, mold opening control is performed at the mold opening speed Vm, and based on a current mold opening speed Vd and a current mold opening position Xd, which are both detected, a deceleration starting position Xmc of the deceleration section Zmd where a current mold opening speed Vd becomes a zero (O) at a virtual stop position Xso 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 opening position Xd, a speed command value Dm corresponding to the speed control pattern A is obtained sequentially by calculation, and according to the speed command value Dm deceleration control is performed. Upon reaching a last-transition speed Vc, a predetermined stop controlling processing is performed.