To allow a back wave where a coupling device for a vehicle seat is laser welded to a member to be coupled to be viewed from outside.

A reclining deice 4 composed as a coupling device for a vehicle seat has: a disk-shaped ratchet 10 integrally coupled to a back frame 2f composing a framework of a seat back 2; and a disk-shaped guide 20 integrally coupled to a cushion frame 3f composing a framework of a seat cushion 3. The ratchet 10 and the guide 20 are assembled so that they can relatively rotate to each other and in the ratchet 10, a dowel 13 projecting to an outer panel side from a disk portion 11 is formed. The dowel 13 is diagonally laser welded while abutting on the surface of the back frame 2f, so that a back wave Wu by the welding is formed while exposed to an outer peripheral surface where the dowel 13 projects.