In a direct stimulus value reading type colorimetric photometer, first, second, and third colorimetric optical systems have spectral responsivities approximate to first, second, and third parts of the color matching function, respectively. A deriving unit derives a colorimetric value corresponding to a case in which the color matching function is selected as an evaluation function for colorimetry and a photometric value corresponding to a case in which the spectral luminous efficiency is selected as an evaluation function for photometry (i.e. “CASE”) from three signals. The spectral luminous efficiency is not consistent with any one of the first, second, and third parts. A fourth colorimetric optical system may have spectral responsivity approximate to the spectral luminous efficiency, and the deriving unit may derive the colorimetric value corresponding to the CASE from a fourth signal.