PURPOSE: To assemble an optical connector with high accuracy, by providing a means to turn the beams of a light emitting source capable of a positional control into parallel beams, a rotor having a lens chucking means set on an optical path and a prescribed measuring means set on a fixed board opposite to the rotor.

CONSTITUTION: The flat characteristics are obtained by turning a rotor 4 while monitoring the beam sent from an optical fiber 5 of a light source. Then a coincidence is obtained between the fiber 5 and the axial core plus angle of the rotor 4. An optical connector C is fixed to a fixing means 11 on a fixed board 10, and a lens L is attached to a collet 9. Then three sensors S calibrated previously are set opposite to a flange face 8 to be made parallel to the board 10, and the outputs of these three sensors are set equal to each other by means of a stage 13. An X-Y stage 14 is shifted to obtain the maximum output of the connector C. Thus the assembly is over. In such way, an optical connector is assembled with high accuracy.