PURPOSE: To improve precision and effect of maintainance work and enhance safety thereof by comprising the check of good precision performed with image over approximately total length of a wire rope monitored by a TV camera and the size of dia., etc., analyzed by signals from this image and the checked results reserved as records.

CONSTITUTION: Hoisting and lowering operation of a crane is performed to monitor the surface of a wire rope 2 using TV cameras 14a, 14b that image the state of broken element wires, affected rust, wear, corrosion, deformation and, etc., in a monitor TV 18. Also, image signals form an image sensor 13a is treated electrically by a picture processing device 17 to enumerate the dia. and the wear extent of the wire rope 2 through an enumeration means and additionally to detect easily and precisely such defects as rust, corrosion, broken element wires, wear, deformation and, etc., in accordance with comparison data through a defect detecting means for the wire rope 2. The image signals and enumerated data are recorded in a recorder 19 for reserving the results of check.