An optical device includes: a base 10; an optical element chip 5 mounted on the base 10; an integrated circuit chip 50 bonded to the back surface of the optical element chip 5; and a transparent member (window member 6). An interconnect 12 is buried in the base 10. The interconnect 12 has an inner terminal portion 12a, an outer terminal portion 12b and an intermediate terminal portion 12c. Pad electrodes 5b on the optical element chip 5 are connected to the inner terminal portion 12a via bumps 8. Pad electrodes 50b on the integrated circuit chip 50 are connected to the intermediate terminal portion 12c via fine metal wires 52. The integrated circuit chip 50 equipped with peripheral circuits and other circuits and the optical element chip 5 are combined into one package.