An example of an optical device of the present disclosure includes a substrate, an obverse-surface conductive layer, a reverse-surface conductive layer, a first conductive part, an optical element and a reflector. The first conductive part extends through the substrate and overlaps with a first obverse-surface conducting region of the obverse-surface conductive layer and the reverse-surface conductive layer as viewed in a thickness direction of the substrate. The reflector has an inner surface that surrounds the optical element as viewed in the thickness direction. The optical element is located on first obverse-surface conducting region, and the second obverse-surface conducting region is located between the first obverse-surface conducting region and the inner surface of the reflector as viewed in the thickness direction. A second obverse-surface conducting region of the obverse-surface conductive layer is spaced apart from the inner surface of the reflector as viewed in the thickness direction.