In a line sensor including color filters periodically disposed in a light-receiving-element row, a “mixture of colors” problem occurs when light that has been transmitted through a color filter differing from a color filter corresponding to a light receiving element is incident upon the light receiving element. To prevent the “mixture of colors” from occurring, in a CMOS sensor 107 including a light-receiving-element row in which a plurality of photodiodes 1204 are disposed side by side in a main scanning direction and a plurality of color filters 1202 that are disposed in correspondence with the plurality of photodiodes 1204, the center of each color filter 1202, other than the center color filter that corresponds to the center photodiode of the light-receiving-element row, is displaced in a direction toward the center of the light-receiving-element row from the center of the photodiode 1204 corresponding to the color filter.