RECLINING DEVICE AND SEAT

Strength of an internal gear including locking internal teeth and memory internal teeth is increased, and deformation when a large load is applied to each of the locking internal teeth and the memory internal teeth is inhibited. In the internal gear (40), a thin annular portion (41) and a thick annular portion (42) whose outside diameters are the same and whose inside diameters are different are continuously provided integrally in an axial direction, and an outer peripheral surface (40a) of the thin annular portion (41) and the thick annular portion (42) is formed in a substantially L shape in a flush cross section. Therefore, a conventionally substantially convex section formed with the memory internal teeth does not become the weak point in terms of strength. In the present invention, since an axial outer end surface of the thick annular portion (42) of the internal gear (40) is formed to be substantially flat, the coupling cover member (50) is fixed to the thick annular portion (42) to be coupled to a frame of a seat cushion or a seat back. Since the coupling can be performed with the thick annular portion (42) interposed, high coupling strength can be obtained.