A method for manufacturing an optical device, the method includes the steps of: forming a multilayer film, including forming a first mirror above a substrate, forming an active layer above the first mirror, forming a second mirror above the active layer, forming a semiconductor layer on the second mirror, and forming a sacrificial layer on the semiconductor layer; conducting a reflection coefficient examination on the multilayer film; patterning the multilayer film to form a surface-emitting laser section having the first mirror, the active layer and the second mirror, and a diode section having the semiconductor layer; and removing at least a portion of the sacrificial layer to expose at least a portion of an upper surface of the semiconductor layer, wherein an optical film thickness of the semiconductor layer is formed to be an odd multiple or an even multiple of λ/4, where λ is a design wavelength of light emitted by the surface-emitting laser section, andan optical film thickness of the sacrificial layer is formed not to be an odd multiple or an even multiple of λ/4.