PURPOSE: To accurately detect the slack of a suspending cable by providing a transmitter for transmitting a signal passing in parallel to a drum axis and directly outside of the suspending cable in the outer circumference of a winding drum.

CONSTITUTION: An elevating base moved up and down along a mast 15 of a stacker crane is elevatably suspended via a suspending cable 64 wound on a winding drum 84 in an elevating device 61. The suspending cable 64 is fixed at the other end thereof to the winding drum 84 and is wound into a single layer on the drum 84. A transmitter 87 for transmitting a signal of light, a sound wave, an electric wave or the like passing in parallel to the axis of the drum 84 and directly outside of the suspending cable 64 on the drum 84 is provided outside of a winding position 86 of the suspending cable 64, and a receiver 88 is provided on a drum supporting bracket 83. The slack of the suspending cable 64 is detected by a receiver 88 based on interruption of the signal of the transmitter 87 to generate an alarm signal.