A seat reclining apparatus for a vehicle, comprising: a first arm configured to be fixedly attached to one of a seat cushion and a seatback, the first arm including a guide wall; a second arm configured to be fixedly attached to the other one of the seat cushion and the seatback, the second arm including internal teeth and being rotatably supported by the first arm; a pawl arranged in an accommodating space formed between the first arm and the second arm, the pawl including external teeth which are engageable with and disengageable from the internal teeth, the pawl being arranged in a manner that movement of the pawl in a radial direction of the first arm is guided by the guide wall; a cam rotatably arranged in the accommodating space at a radially inner side relative to the pawl, the cam engaging with the pawl, causing the pawl to advance and retract along the guide wall, and causing the internal teeth and the external teeth to mesh with and unmesh from each other as the cam rotates; a recessed portion provided at the second arm concentrically with the internal teeth in a manner that the recessed portion is recessed in a direction of an axis line of the second arm, the recessed portion including a restricting portion provided in a range of a predetermined angle and protruding inwardly in a radial direction of the second arm; an engaging portion formed at the pawl in a manner that the engaging portion faces the recessed portion in a radial direction of the pawl at a position different, in the direction of the axis line, from an engagement position at which the pawl and the cam engage with each other, the engaging portion restricting the external teeth and the internal teeth from meshing with each other by being in contact with the restricting portion; a hinge cam integrally rotatably fitted in the cam by insertion in the direction of the axis line, and including a first shaft portion, a second shaft portion and a flange portion, the first shaft portion penetrating through the first arm and rotatably supported at the first arm, the second shaft portion penetrating through the second arm and journaled at the second arm, the flange portion being accommodated in a space defined by the recessed portion at a radially inner side relative to the engaging portion; and a biasing member biasing and rotating the hinge cam at the first shaft portion in one direction and causing via the cam the pawl to move in a radial direction in which the external teeth and the internal teeth mesh with each other or in which the engaging portion and the restricting portion are in contact with each other. a first arm configured to be fixedly attached to one of a seat cushion and a seatback, the first arm including a guide wall; a second arm configured to be fixedly attached to the other one of the seat cushion and the seatback, the second arm including internal teeth and being rotatably supported by the first arm; a pawl arranged in an accommodating space formed between the first arm and the second arm, the pawl including external teeth which are engageable with and disengageable from the internal teeth, the pawl being arranged in a manner that movement of the pawl in a radial direction of the first arm is guided by the guide wall; a cam rotatably arranged in the accommodating space at a radially inner side relative to the pawl, the cam engaging with the pawl, causing the pawl to advance and retract along the guide wall, and causing the internal teeth and the external teeth to mesh with and unmesh from each other as the cam rotates; a recessed portion provided at the second arm concentrically with the internal teeth in a manner that the recessed portion is recessed in a direction of an axis line of the second arm, the recessed portion including a restricting portion provided in a range of a predetermined angle and protruding inwardly in a radial direction of the second arm; an engaging portion formed at the pawl in a manner that the engaging portion faces the recessed portion in a radial direction of the pawl at a position different, in the direction of the axis line, from an engagement position at which the pawl and the cam engage with each other, the engaging portion restricting the external teeth and the internal teeth from meshing with each other by being in contact with the restricting portion; a hinge cam integrally rotatably fitted in the cam by insertion in the direction of the axis line, and including a first shaft portion, a second shaft portion and a flange portion, the first shaft portion penetrating through the first arm and rotatably supported at the first arm, the second shaft portion penetrating through the second arm and journaled at the second arm, the flange portion being accommodated in a space defined by the recessed portion at a radially inner side relative to the engaging portion; and a biasing member biasing and rotating the hinge cam at the first shaft portion in one direction and causing via the cam the pawl to move in a radial direction in which the external teeth and the internal teeth mesh with each other or in which the engaging portion and the restricting portion are in contact with each other.