PURPOSE: To align correctly a microlens to a light emitting part by making a light emitting diode chip emit a light, and measuring an intensity of its light by a photodetector, in the course of a process for sticking the microlens onto the light emitting part of the light emitting diode chip by making it contact and adhere by pressure through an adhesive agent.

CONSTITUTION: An adhesive agent 3 is dripped down onto a light emitting part 2 of a light emitting diode chip 1, and a microlens 5 is held by a collet 4 of a vacuum chuck, moved to right above the light emitting part 2, pressed against the adhesive agent 3 and adhered. In this case, a photodetector or an optical fiber provided with the photodetector on its terminal is provided downward in the collet 4, the light emitting diode chip is made to emit a light, an intensity of a light which passes through the microlens 5 and is made incident to the collet 4 is measured by the photodetector, and at a position where the optical intensity becomes maximum, the microlens 5 is pressed against the adhesive agent 3 on the light emitting diode chip 1 and adhered.