PURPOSE: To execute centering with high accuracy and to drastically reduce the number of working processes by effectively radiating ultraviolet rays to the peripheral part of an ultraviolet light polymerization type adhesive for adhering or joining.

CONSTITUTION: Ultraviolet rays 68 made incident on the effective diameter part of a lens frame 21 is transmitted through a lens 2, reflected by reflecting faces 66a, 66b, converged into a ring band-like optical ring, and then radiated to the engaging part of the lens frame 21 with the lens, i.e. a portion applied with the adhesive 29. Since the adhesive 29 is instantaneously solidified, the lens 2 can be fixed and held on the lens frame 21 under the centering state with high accuracy. A joining agent is dropped on the upper surface of the lens 2, a lens 3 is mounted on the lens 2. While executing foaming and wedging, the lens 3 is centered, and at the time of completing the centering, ultraviolet rays are radiated from the lower part to solidify the joining agent instantaneously. Thereby, a demerit weakening joining force near the peripheral part of the lens can be compensated by the action of a reflection mirror and more complete joining can be attained.