The present invention provides a highly reliable spectral module. When light L1 proceeding to a spectroscopic unit (4) passes through a light transmitting hole (50) in the spectral module (1) in accordance with the present invention, only the light having passed through a light entrance side unit (51) formed such as to become narrower toward a substrate (2) and entered a light exit side unit (52) formed such as to oppose a bottom face (51b) of the light entrance side unit (51) is emitted from a light exit opening (52a). Therefore, stray light M incident on a side face (51c) or bottom face (51b) of the light entrance side unit (51) is reflected to the side opposite to the light exit side unit (52) and thus is inhibited from entering the light exit side unit (52). Therefore, the reliability of the spectral module (1) can be improved.