A problem addressed by the present invention is to reduce the influence of stray light incident on each light-receiving element in the case of receiving each wavelength of light using a plurality of light-receiving elements. The multichannel spectrophotometer according to the present invention is a detector for simultaneously detecting the entirety of wavelength-dispersed light obtained by introducing light from a sample to a light-dispersing element (16) and dispersing this light into wavelengths by the light-dispersing element (16), including: a multichannel-type detector (17) including a plurality of light-receiving elements arranged in a one-dimensional form in a wavelength-dispersing direction of the light-dispersing element; a light amount calculator (221) for calculating the amount of light from a detection signal of each of the plurality of light-receiving elements (PD); a spectrum creator (222) for creating, from the amounts of light calculated by the light amount calculator (221), a spectrum showing a relationship between wavelength and the amount of light; and a computing section (224) for estimating, from the spectrum, the amount of stray light incident on each light-receiving element (PD) and correcting the spectrum by subtracting, from the amount of wavelength-dispersed light incident on each light-receiving element, the amount of stray light.