Optical receptacle and optical module

An optical receptacle optically couples a light emitting element and an optical transmission member when disposed between the light emitting element and the optical transmission member, and includes a first optical surface that allows incidence of light emitted from the light emitting element; a second optical surface that emits, toward the optical transmission member, light emitted from the light emitting element and advanced inside the optical receptacle; and a diffraction grating disposed on the first optical surface, on the second optical surface, or on a light path between the first and second optical surfaces. The diffraction grating is configured such that zero-order diffraction light of the light emitted from the light emitting element reaches an end portion of the optical transmission member, and that primary diffraction light of the light emitted from the light emitting element does not reach the end portion of the optical transmission member.