Seat reclining device

In an eccentric-drive equipped seat reclining device including a cover (2) having internal teeth (2a), a base member (1), an external gear (6) having fewer external teeth (6a) than the number of the internal teeth (2a), a pair of wedge-shaped members (8) and a guide plate (9) located in an eccentric space (7) defined between the cover (2) and the external gear (6), a spring (10) biasing the wedge-shaped members (8) apart from each other, and a driving member (5) for circumferentially pushing the pair of wedge-shaped members (8), the external gear (6) has a cylindrical protrusion (6d). The base member (1) has a first annular axially-recessed portion (1b) for press-fitting the external gear (6) to the base member (1), a second annular axially-recessed portion (1c) for accommodating the cylindrical protrusion (6d), and a third annular axially-recessed portion (1d) for accommodating the spring (10). Protrusions (1e), formed integral with an annular outer peripheral portion (1f) of the backface of the second annular axially-recessed portion (1c), are fitted to respective recessed portions (3a) of a seat-cushion side arm (3).