PURPOSE: To form a diffusion reflecting layer of high accuracy with high productivity by applying energy to a UV-curing resin with an arbitrary UV transmitting pattern.

CONSTITUTION: A reflecting plate 16 is coated with a UV-curing resin 20 and this resin 20 is irradiated with UV through a mask 24 having a prescribed UV transmitting pattern to cure a part of the resin 20 corresponding to the pattern. A transparent plate 10 is then put on the coated reflecting plate 16 and curing energy is applied to the uncured UV-curing resin 20 to adhere the resin 20 to the plate 10 as well as to cure the resin 20. A diffusion reflecting layer 18 of high accuracy can be formed with high productivity.