PROBLEM TO BE SOLVED: To reduce an influence on an optical device caused by stress variation on a resin sealing body due to an environmental change and similar change.SOLUTION: An optical device includes a substrate 11, a semiconductor lamination portion formed on the substrate 11 and configured to receive or emit a light, a protective layer 3 that has a shape to cover an entire surface of the semiconductor lamination portion, a mold resin 6 configured to seal the protective layer 3 and the substrate 11 excluding a surface of the substrate 11 on an opposite side of a surface on which the semiconductor lamination portion is formed. The light is entered or emitted from a side of the substrate 11, and the mold resin 6 includes a through hole 61 configured to pass through from a top surface of the mold resin 6 to the protective layer 3. A deformation of the mold resin 6 is reduced by the protective layer 3 and the through hole 61. Then, stress variation acting on an active portion 12 including the semiconductor lamination portion can be reduced.