A method of manufacturing an optical module including a light-transmitting member allowing passage of light having a prescribed wavelength, a base member allowing no passage of light having the prescribed wavelength, wherein the base member is located on a side of a back surface of said light-transmitting member, an optical semiconductor device mounted on a front surface of said base member and sealed with said light-transmitting member, a light guide path forming member allowing no passage of light having the prescribed wavelength, wherein the light guide path forming member is located on a side of a front surface of said light-transmitting member, and an adhesion layer formed as a result of curing of an adhesive containing a light curing resin composition cured by irradiation with light having said prescribed wavelength, for adhering said light-transmitting member and said light guide path forming member to each other, comprising: mounting said optical semiconductor device on said front surface of said base member; sealing said front surface of said base member on which said optical semiconductor device has been mounted with said light-transmitting member formed in a layered manner, by forming, on said front surface in said layered manner, a light-transmitting composition serving as a base material in which a filler is dispersed in order to scatter light emitted toward said light-transmitting member in said light-transmitting member; applying said adhesive to at least any of said front surface of said light-transmitting member and a back surface of said light guide path forming member; stacking said light guide path forming member on said front surface of said light-transmitting member in such a manner that said front surface of said light-transmitting member and said back surface of said light guide path forming member are opposed to each other with applied said adhesive being interposed; and adhering said light-transmitting member and said light guide path forming member to each other by irradiating said light-transmitting member with light having said prescribed wavelength laterally from a side of said light-transmitting member so as to cure said adhesive and to fix said light-transmitting member and said light guide path forming member to each other. mounting said optical semiconductor device on said front surface of said base member; sealing said front surface of said base member on which said optical semiconductor device has been mounted with said light-transmitting member formed in a layered manner, by forming, on said front surface in said layered manner, a light-transmitting composition serving as a base material in which a filler is dispersed in order to scatter light emitted toward said light-transmitting member in said light-transmitting member; applying said adhesive to at least any of said front surface of said light-transmitting member and a back surface of said light guide path forming member; stacking said light guide path forming member on said front surface of said light-transmitting member in such a manner that said front surface of said light-transmitting member and said back surface of said light guide path forming member are opposed to each other with applied said adhesive being interposed; and adhering said light-transmitting member and said light guide path forming member to each other by irradiating said light-transmitting member with light having said prescribed wavelength laterally from a side of said light-transmitting member so as to cure said adhesive and to fix said light-transmitting member and said light guide path forming member to each other.