PURPOSE: To attempt to make positioning surely and easily by providing, a taper part slipping out from a locking hole by means of external force in lead-in direction, on a locking claw provided to the elastic arm member of a first locking member for positioning, and suppressing deformation of the first locking member by means of a second locking member having a similar taper part and a locking part for engaging with another locking hole.

CONSTITUTION: A locking claw 4 facing to locking holes 2A,2B of a shaft 1 is provided on the top end of an arm member, having elasticity, of a first locking member 3. A taper part 4A slipping out from the locking holes 2A,2B by means of external force in 9 direction is formed to the locking claw 4. Meanwhile, a second locking member 5 is arranged in contact with the first locking member 3, deformation of the locking claw 4 at a time of slipping out from the locking hole 2A is suppressed, and a locking part 6 for engaging with the locking hole 2B and having the same taper part 6A as the locking claw 4 is provided to the second locking member 5. Therefore, both locking members 3,5 prevent the locking claws 4,6 from slipping out from the locking holes 2A,2B in cooperation with each other, lead-in movement to an apointed position is facilitated, and movement after positioning can be prevented.