To solve such a problem that the output light of a spectrum light source device used for color evaluation has a light intensity distribution depending on wavelength, that is, color irregularity.

The spectrum light source device includes: a light source which emits light source light having a predetermined wavelength band; a modulation element which reflects or transmits the light source light so that a designated specific region is different from other regions in a plane region on which the light source light is radiated; a wavelength dispersion element which disperses in wavelength the light source light reflected or transmitted in the specific region; a slit which is positioned relative to the wavelength dispersion element and transmits a porion of wavelength light of the light source light which is dispersed with the wavelength dispersion element; and a control part which controls the specific region of the modulation element.