A mounting structure for an optical module includes a light emitting element, a submount board on which the light emitting element is mounted, a main board on which the submount board is mounted, a light guide member provided on the main board, and a diffraction grating optical coupler provided on the main board and connected to the light guide member. The submount board and the main board are bonded to each other on a surface of the submount board different from a surface on which the light emitting element is mounted.