In the seat reclining device (E) of the invention, the working mechanism (50) is composed of a cam member operating lever (51) having a base portion supported rotatably on the base plate (10), and the free end side being coupled with the cam member (40) through a coupling pin (42), biased in the locking direction by a first biasing mechanism and an unlocking lever (52) having the base portion rotatably supported by the same shaft (56) as the cam member operating lever (51), and the intermediate portion provided with a pinhole (52a) for freely fitting a coupling pin (42), biased in the locking direction by a second biasing mechanism, and the manipulating mechanism (60) is composed of a wire (62) having one end coupled to the unlocking lever (52) and the other end to the unlocking lever knob (61) provided in the upper part of the seat back side (71), and therefore the seat back (71) can be locked in the initial stage at the rear inclined position from the lock free state, completely regardless of the inertial force of the unlocking lever knob (61) and the sliding resistance of the wire (62).