After a deceleration limit switch (29) has been restored in performing the control for returning to origin, a position of lattice point at which a one-turn signal (RTS) is generated from the rotary encoder (24) for the first time is set to be the origin. In an origin return mode (ZRN = 1) in which a mechanical moving part returns to the origin, a numerical control unit (21) regards a position at which a rotary encoder (24) generates the one-turn signal (RTS) as zero, and monitors an instructed position REF0 until a next one-turn signal is generated for every predetermined period of time, and repeats the monitoring of such an instructed position until the moving part reaches near the origin. When the moving part approaches the origin and the deceleration limit switch (29) is restored, the instructed position REF0 at the first time is found for every DELTAT, and a distance (N - REF0) from the instructed position to a position at which a next one-turn signal is generated is sent as a final instructed moving amount to a digital servo circuit (22), so that the moving part returns to the origin. Here, N represents a distance between the lattice points.