An improvement is added to a spectroscope for performing wavelength dispersion of measured light with a wavelength dispersion element and receiving the light at a light reception element. The spectroscope has a first compound lens made up of a plurality of lenses for converting measured light into parallel light and emitting the parallel light to the wavelength dispersion element; a second compound lens made up of a plurality of lenses for gathering the measured light subjected to the wavelength dispersion in the wavelength dispersion element and causing the light reception element to receive the light; and a base for fixing the wavelength dispersion element, the first compound lens, and the second compound lens. The linear expansion coefficient of the compound focal length of the first compound lens, the linear expansion coefficient of the compound focal length of the second compound lens, and the linear expansion coefficient of a material forming the base are substantially equal.