To dispense with any lockup of one end of a clutch spring by installing a large diametral part, being concentric with a holder part and almost according with an outer diameter of this holder part projecting outward from the holder part of a clutch shaft, and winding a clutch spring simultaneously on both peripheral part of this large diametral part and the holder part.

A holder part 3 is provided with a small diametral part 11 at one end side, and as to a clutch shaft 4, a large diametral part 12 forming the same outer diameter as that of almost the small diametral part 11 is formed in a part projected outward from the small diametral part 11, and they are situated on the same shaft, whereby the small diametral part 11 and the large diametral part 12 are contacted with each other, thereby mutually regulating their axial movements. The clutch spring 10 is simultaneously wound on both outer boundaries of the small diametral part 11 and the large diametral part 12, and an inner diameter at the usual time is made to be somewhat smaller than each outer diameter of the small diametral part 11 and the large diametral part 12, and the inner circumferential surface is contacted close to each outer circumferential surface of both the small and large diametral part 11 and 12. In this connection, one end of the clutch spring 10 is situated on the circumference of the large diametral part 12 in a state of nonfixation.