A vehicle seat reclining device comprising: a first bracket adapted to be fixed to either one of a seat cushion and a seat back; a pair of guide portions provided on the first bracket and forming a guide groove; a second bracket adapted to be fixed to the other one of the seat cushion and the seat back and having internal teeth, wherein as the second bracket rotates relative to the first bracket, an angle of inclination of the seat back with respect to the seat cushion is adjustable; a pawl (41 A, 41 B) that has external teeth, which can engage with or disengage from the internal teeth of the second bracket, wherein the pawl (41 A, 41 B) is guided by the guide groove to move in a radial direction; a cam member (42, 43) rotationally provided in the first bracket in engagement with the pawl (41 A, 41 B); an urging member for urging the cam member (42, 43) in a direction of rotation to move the pawl (41 A, 41 B) in such a direction that the external teeth and the internal teeth engage with each other; and a manipulation member, which causes the cam member (42, 43) to rotate against an urging force of the urging member to move the pawl (41 A, 41 B) in such a direction that the external teeth and the internal teeth disengage from each other, wherein each of the guide portions has a tip end portion located closer to the internal teeth in the radial direction and has a protruding portion at least at the tip end portion, a fulcrum of inclination of the pawl (41 A, 41 B) with respect to the guide portion possibly occurs during disengagement of the external teeth and the internal teeth from each other, and the protruding portion protrudes in a circumferential direction such that the fulcrum of inclination is located in a place closer to the internal teeth than a point of intersection between the guide portion and a normal to a surface where the external teeth and the internal teeth engage with each other. a first bracket adapted to be fixed to either one of a seat cushion and a seat back; a pair of guide portions provided on the first bracket and forming a guide groove; a second bracket adapted to be fixed to the other one of the seat cushion and the seat back and having internal teeth, wherein as the second bracket rotates relative to the first bracket, an angle of inclination of the seat back with respect to the seat cushion is adjustable; a pawl (41 A, 41 B) that has external teeth, which can engage with or disengage from the internal teeth of the second bracket, wherein the pawl (41 A, 41 B) is guided by the guide groove to move in a radial direction; a cam member (42, 43) rotationally provided in the first bracket in engagement with the pawl (41 A, 41 B); an urging member for urging the cam member (42, 43) in a direction of rotation to move the pawl (41 A, 41 B) in such a direction that the external teeth and the internal teeth engage with each other; and a manipulation member, which causes the cam member (42, 43) to rotate against an urging force of the urging member to move the pawl (41 A, 41 B) in such a direction that the external teeth and the internal teeth disengage from each other, wherein each of the guide portions has a tip end portion located closer to the internal teeth in the radial direction and has a protruding portion at least at the tip end portion, a fulcrum of inclination of the pawl (41 A, 41 B) with respect to the guide portion possibly occurs during disengagement of the external teeth and the internal teeth from each other, and