A device for adjusting an optical axis of a headlight of a vehicle, the device comprising: a housing unit (9, 10); a motor that is arranged in the housing unit (9, 10); a shaft that moves back and forth with respect to the housing unit (9, 10); a driving-force transmitting mechanism that is arranged between the motor and the shaft, and that transmits a driving force of the motor to the shaft; and a plurality of terminals for supplying an electric power to the motor, wherein the driving-force transmitting mechanism includes either one of a gear or a gear group (29, 30, 31) mounted around the output shaft of the motor, and a worm wheel that engages with either one of the gear or the gear group (29, 30, 31), being screwed into the housing unit (9, 10) in a direction in which the shaft moves back and forth, the worm wheel moving back and forth with the shaft while rotating with respect to the housing unit (9, 10) by a screw movement, an axial direction of an output shaft of the motor is perpendicular or substantially perpendicular to an axial direction of the shaft, and a shape of a layout of the terminals is substantially symmetric with respect to a vertical line passing through a center of the shaft characterized in that the device further comprises a cylindrical rod unit (33, 34) having a first rod and a second rod detachably integrated to constitute the cylindrical rod unit (33, 34), wherein said first rod has a a ring-shaped pressing portion integrally formed in the middle of the outer peripheral surface of the first rod and said second rod has a protrusion portion integrally arranged on an outer peripheral surface of the top of the second rod in a radial direction thereof, wherein the cylindrical rod unit (33, 34) is arranged in the worm wheel such that the ring-shaped pressing portion and the protrusion portion presses against both ends of the worm wheel. a housing unit (9, 10); a motor that is arranged in the housing unit (9, 10); a shaft that moves back and forth with respect to the housing unit (9, 10); a driving-force transmitting mechanism that is arranged between the motor and the shaft, and that transmits a driving force of the motor to the shaft; and a plurality of terminals for supplying an electric power to the motor, wherein the driving-force transmitting mechanism includes either one of a gear or a gear group (29, 30, 31) mounted around the output shaft of the motor, and a worm wheel that engages with either one of the gear or the gear group (29, 30, 31), being screwed into the housing unit (9, 10) in a direction in which the shaft moves back and forth, the worm wheel moving back and forth with the shaft while rotating with respect to the housing unit (9, 10) by a screw movement, an axial direction of an output shaft of the motor is perpendicular or substantially perpendicular to an axial direction of the shaft, and a shape of a layout of the terminals is substantially symmetric with respect to a vertical line passing through a center of the shaft characterized in that the device further comprises a cylindrical rod unit (33, 34) having a first rod and a second rod detachably integrated to constitute the cylindrical rod unit (33, 34), wherein said first rod has a a ring-shaped pressing portion integrally formed in the middle of the outer peripheral surface of the first rod and said second rod has a protrusion portion integrally arranged on an outer peripheral surface of the top of the second rod in a radial direction thereof, wherein the cylindrical rod unit (33, 34) is arranged in the worm wheel such that the ring-shaped pressing portion and the protrusion portion presses against both ends of the worm wheel.