An optical sensor has a glass base having a concave portion, and a glass lid is bonded to the base and overlies the concave portion to form a cavity portion. A photoelectric conversion element id accommodated in the cavity portion. Internal wirings are each connected at one end to the photoelectric conversion element and extend through notches each formed at a corner of a peripheral edge along an outside surface of the base. The other ends of the internal wirings are connected inside the notches to external wirings that extend along an outside surface of the base and terminate in external terminals.