A 4-line CCD sensor according to one embodiment of the present invention has a monochromic reading line sensor section and a color reading line sensor section. This 4-line CCD sensor is characterized in that amplification factors for amplifiers 1 to 4 are set so that the amplitude of an output signal from the monochromic reading line sensor section is the same as that of each output signal from the color reading line sensor section. This 4-line CCD sensor is characterized in that the amplification factors for the amplifiers 1 to 4 are set so that the amplitude of each output signal from the color reading line sensor section is smaller than that of an output signal from the monochromic reading line sensor section.