PURPOSE: To eliminate a runaway state where a machine movable part is not decelerated when a grid system reference point is recovered and to improve operability.

CONSTITUTION: A limit dock for recovery start prohibition area setting bestriding the prescribed location on the side of the recovering direction from the start end location of a limit dock setting a deceleration area and a stroke termination location is added and this limit dock is detected by a limit switch. When this detection signal is turned on or a recovery start location exists in a prohibition area, normal recovery start processings (steps S2 to S6) are interlocked, a machine driving part is made to once move an anti-recovering direction and is made to retreat to the outside of a prohibition area (steps S7, S8). After this retreat, a normal recovering processing is performed.