The beam distributor includes a housing, at least one beam entrance, two or more beam exits, a motor, and a beam turning part fixed to a rotary axis member of the motor and changing a direction of a beam input to the inside of the housing through the beam entrance so as to guide the input beam to the beam exit. A rotary axis of the motor is arranged parallel to an optical axis of the beam so as to input the beam to the beam turning part at a constant angle independently of a rotational angle about the rotary axis of the motor. The beam exit is arranged in a direction to which the direction of the beam is changed by the beam turning part in response to rotation of the rotary axis member. A storage stores an angular information recorded in advance about the rotary axis.