To suppress an increase in the slack of a rope such as a hose wound on a winding drum.

When the outermost diameter size of a rope 3 wound on a winding drum 5 is determined to be a predetermined size or larger, the rotation of a driving source 7 is stopped or reversed. Thus, when the occurrence of great slack in the rope 3 wound on the winding drum 5 can be estimated, the rotation of the driving source 7 is stopped or reversed to suppress an increase in the slack of the rope 3.