A spectrometer includes a support having a bottom wall part and a side wall part surrounding a spectroscopic space, a cover arranged on an opening part formed by the side wall part and provided with a light transmitting part, a joining member arranged between the cover and the opening part, a light detection element supported by the side wall part between the spectroscopic space and the cover, and an optical function part provided on a surface of the bottom wall part. A vent is provided in at least one of the support, the cover, and the joining member. The vent is open to an outside and a space defined by the support, the cover, and the light detection element. The space communicates with the spectroscopic space.