An endoscope having a color space conversion circuit performs a matrix calculation according to RGB signals and matrix data respectively corresponding to signals in wavelength ranges is provided with a wavelength memory section having a default data memory area, which stores a default value representing a wavelength range selected by a wavelength selection section, and a changed-wavelength saving area that stores a wavelength range selected by the wavelength selection section after changed from the wavelength range represented by the default value. Subsequently, at least a part of the wavelength range stored in the changed-wavelength saving area is rewritten by a reset section into the default value stored in the default data memory area.