PURPOSE: To measure electric resistance on the surface of an optional strand in removing the insulating film from the insulated strand constituting a cable conductor.

CONSTITUTION: A measuring device 10 is provided with a tube member 11 so that the strand of a cable can be inserted into a through hole 12 inside it, and contacts 14, 14a are protruded to the inside of the through hole 12. The contacts 14, 14A are pressed to both side portions of the strand and connected to a measuring unit 17 via electric wires 16, 16a. The resistance value is measured between two points on both sides of the strand while the tube member 11 is moved along the strand of a cable conductor, and the removed state of an insulating film can be electrically detected.