The designated speeds of a plurality of blocks are read beforehand, deceleration start positions are calculated to maintain the servo system at a speed below the designated speeds of the blocks read beforehand at the start positions of the previously read blocks, and the servo system is decelerated from the calculated deceleration start positions, whereby the servo system speed is kept below the designated speeds of all of the blocks and the deceleration of the speed of the servo system is controlled with a high degree of accuracy.