An endoscope apparatus comprises: an endoscope comprising an imaging device that forms a color image signal of a body to be observed a storage portion that stores matrix data for forming a spectral image based on the color image signal a spectral image-forming circuit that conducts matrix calculation based on the color image signal by using the matrix data of the storage portion and forms at least one spectral image signal each of which corresponds to an arbitrarily selected wavelength range and an amplifier circuit that amplifies said at least one spectral image signal formed by the spectral image-forming circuit.
