A dispensing apparatus comprising: an output shaft having screw grooves on an outer circumferential surface; a rotary actuator including a reduction gear and configured to rotate the output shaft around an axis of the output shaft; a piston screwed into the screw grooves of the output shaft and configured to move back and forth along an axial direction of the output shaft by drive of the rotary actuator; a nozzle disposed at a leading end of the dispensing apparatus and configured to suck and spout liquid in accordance with the back and forth movement of the piston; and an actuator case configured to cover an outer circumferential portion of the reduction gear, and configured to support a proximal end portion of the output shaft by a leading end portion of the actuator case such that the proximal end portion of the output shaft is engaged with a leading end portion of the reduction gear in a state capable of transmitting the drive, characterized in that the reduction gear is equipped with a planetary gear mechanism having a cylindrical ring gear with a bottom, and has a drive shaft unit which forms the leading end portion of the reduction gear by protruding toward the leading end side in a center portion of a bottom wall outer surface of the ring gear, and is partially formed with a planar contact surface, and when the drive shaft unit relatively enters an output recess formed in the proximal end portion of the output shaft and the drive shaft unit rotates around an axis, the actuator case rotatably supports the proximal end portion so as to enable to transmit the drive to the output shaft by the contact surface coming into contact with an inner wall surface of the output recess. an output shaft having screw grooves on an outer circumferential surface; a rotary actuator including a reduction gear and configured to rotate the output shaft around an axis of the output shaft; a piston screwed into the screw grooves of the output shaft and configured to move back and forth along an axial direction of the output shaft by drive of the rotary actuator; a nozzle disposed at a leading end of the dispensing apparatus and configured to suck and spout liquid in accordance with the back and forth movement of the piston; and an actuator case configured to cover an outer circumferential portion of the reduction gear, and configured to support a proximal end portion of the output shaft by a leading end portion of the actuator case such that the proximal end portion of the output shaft is engaged with a leading end portion of the reduction gear in a state capable of transmitting the drive, characterized in that the reduction gear is equipped with a planetary gear mechanism having a cylindrical ring gear with a bottom, and has a drive shaft unit which forms the leading end portion of the reduction gear by protruding toward the leading end side in a center portion of a bottom wall outer surface of the ring gear, and is partially formed with a planar contact surface, and when the drive shaft unit relatively enters an output recess formed in the proximal end portion of the output shaft and the drive shaft unit rotates around an axis, the actuator case rotatably supports the proximal end portion so as to enable to transmit the drive to the output shaft by the contact surface coming into contact with an inner wall surface of the output recess.