A reclining device capable of controlling angles of a seat back of a vehicle is provided. A ratchet plate is superposed on a base plate such that the ratchet plate is rotatable relative to the base plate. An operation shaft is rotatably disposed on the rotation center axis of the ratchet plate. A circular concave is formed on a surface of the ratchet plate opposed to the base plate around the operation shaft. Inside teeth are provided on an inner circumferential wall surface of the concave. Poles having outside teeth on their front end surfaces are disposed on the concave, and the outside teeth of the poles engage with and disengaging from the inside teeth in the radial direction of a teeth end circle. Guide projections provided on the base plate slidingly guide the poles in the radial direction. A cam disposed in a space on the side of rear end surfaces of the poles is rotatable with the operation shaft. A release plate disposed between the ratchet plate and the components of the poles and the cam such that the release plate is rotatable with the cam. Projections engaging with cam grooves are provided at the rotation end of the release plate to release engagement between the inside teeth and the outside teeth.
