PURPOSE: To allow a flexible member to advance on a predetermined route even in the case where connection loosens between toothed members by forming each distal end face of the toothed members into a slant shape, and designing their blade parts to be engaged with the corresponding slits of a lock core.

CONSTITUTION: A flexible member 2 comprises a plurality of toothed members 21, 22, 23, and these are rotatably joined by a pin 24. The foremost toothed member 21 is formed along with a slant tip face. Also, the toothed member 22 is formed together with a blade part 221, and the toothed member 23 is formed with a blade part 231. The blade part 231 is formed to fall on the same plane as the toothed member 23 is engaged with the toothed member 22. Such a flexible member 2 is housed within a casing 26 having an opening end in a manner capable of being pushed out therefrom. Furthermore, the blade part 221 of the toothed member 22 and the blade part 231 of the toothed member 23 are designed to be engaged with the corresponding slits of a lock core, thereby permitting the flexible member 2 to successively advance on a predetermined route even when connection is loosened between the toothed members of the flexible member 2.