a folding biasing unit that supports a seatback so as to be capable of reclining the same to a seat cushion, and biases the seatback to a folded position;

a reclining lock mechanism that is displaced between a lock position where the seatback is locked at an arbitrary position within a reclining range and a lock release position where the lock is released, and exerts a lock biasing force at the lock position; and

a folding operation lever which displaces the reclining lock mechanism to the lock release position, wherein

the reclining lock mechanism is displaced from the lock position to the lock release position when the folding operation lever is operated to a folding operation position, and the seatback is displaced to the folded position by a biasing force of the folding biasing unit,

the seat reclining apparatus further comprises

a neutral position returning unit that retains a releasing lever disposed between the folding operation lever operated to the folding operation position and the reclining lock mechanism at the lock release position when the seatback is positioned on the folding side beyond a predetermined neutral position set within the reclining range, and allows movement of the releasing lever to the lock position when the seatback is positioned on a rearward-inclining side beyond the neutral position,

the neutral position returning unit and the releasing lever are formed as a seat memory unit, and

the seat memory unit comprises

a cylindrical collar which is rotatably supported on a unit fixing base fixed on the seatback side or the seat cushion side to rotate integrally with a shaft, the shaft penetrating the cylindrical collar and being capable of displacing the reclining lock mechanism between the lock position and the lock release position,

the releasing lever which is fixed on the cylindrical collar to rotate integrally,

a folding link lever which is rotatably supported on an outer peripheral face of the cylindrical collar which is provided so as to link the folding operation lever provided to an upper portion of the seatback, which is displaced from a standby position to a lever rotating position against a biasing force of a lever biasing unit when the folding operation lever is operated from a standby position to the folding operation position, and which rotates the releasing lever together in this displacement course to displace the reclining lock mechanism from the lock position to the lock release position,

a cam plate which is rotatably supported to the unit fixing base, and which can be displaced between a lever rotation allowable position where rotation of the folding link lever can be allowed and a lever rotation blocking position where rotation of the folding link lever is blocked when the folding link lever is positioned at the lever rotating position,

a cam biasing unit that biases the cam plate to the lever rotation blocking position side, and

a cam releasing unit that displaces the cam plate from the lever rotation blocking position to the lever rotation allowable position against a biasing force of the cam biasing unit when the seatback is displaced from the folded position to the predetermined neutral position and that retains the cam plate at the lever rotation allowable position when the seatback is positioned on the rearward-inclining side beyond the neutral position.