In an endoscope apparatus, a signal obtained by image pickup by a CCD having a color separation filter is separated into a first luminance signal and a first color difference signal by a Y/C separation circuit, and thereafter converted into three primary color signals and a second color difference signal by a first matrix circuit and a second matrix circuit, and a signal intensity ratio among the three primary color signals is calculated by a signal intensity ratio calculation circuit interposed between the first and the second matrix circuits. Conversion is performed on the first luminance signal and the second color difference signal by a third matrix circuit such that color separation is performed on the first luminance signal according to the signal intensity ratio.
