A seat reclining device includes a ratchet, a guide, and pawls for locking relative rotation between the ratchet and the guide. The ratchet has a second convex portion protruding so as to abut against a ride-up protrusion of a main pawl. The second convex portion has, only in a partial region thereof in the rotation direction, a relief concave portion configured to avoid abutment in the rotation direction between the ride-up protrusion and the second convex portion.