PURPOSE:To obtain excellent reproducibility for the faithful duplication of the pattern of an original disk and superior mass-productivity by making an optical waveguide element which has the fine pattern of a grating coupler, etc., in corresponding fine uneven pattern. CONSTITUTION:The pattern of the original disk 10 in the shape of the optical waveguide element including the fine uneven pattern is transferred onto an optical waveguide layer 12 formed on a substrate 14 by using organic resin, and a mask material 15 which provides an etching selection ratio to the organic resin is formed on the organic resin layer 11 and flattened. Then the mask material 15 is etched back uniformly to form a 1st mask pattern and the organic resin layer 11 is etched to form a 2nd mask pattern on the optical waveguide layer 11. Further, the patterned organic resin layer 11 is used as a mask to form an uneven pattern on the surface of the optical waveguide 12 and the organic resin layer 11 is removed. Consequently, the optical waveguide element is obtained which has superior mass-productivity and high reproducibility and practicability.