PURPOSE: To suspend a lifting operation driven by a hydraulic unit in automatic mode and prevent the generation of accidents when a pallet goes up and down without issuing any command to go up and down.

CONSTITUTION: An ascent switch 22 and a descent switch 23 and an ascent position detector 41 and a descent position detector 42 which detect an ascent position and a descent position of a pallet 2, and what is more, to detect the movement of the pallet from the ascent position and the descent position of the pallet 2, are installed to each of parking lots 1. The detectors 41 and 42 emergency-shut down a motor 39 of a hydraulic pump 31 in a hydraulic unit when they detect an operational failure.