A calculation unit (112) acquires a dedicated base vector based on a known spectral characteristic of a subject as an identification target having the known spectral characteristic from a base vector ROM (114), and acquires a spectral characteristic of an imaging system including a spectral characteristic concerning a color imaging system used for image acquisition of subjects including the subject as the identification target and a spectral characteristic concerning illumination light used when image acquisition of the subjects by the color imaging system from a system spectral characteristic ROM (115). Then, it calculates a weighting factor concerning the dedicated base vector based on an image signal obtained by image acquisition of the subject by the color imaging system, the dedicated base vector, and the spectral characteristic of the imaging system. A normalization unit (116) calculates an identification result of the subject which is the identification target having the known spectral characteristic based on the weighting factor concerning the dedicated base vector, and outputs it as an output signal by an output unit (117).
