An image reading device has a light source section that includes light sources of a plurality of colors and that emits light in one color during a period for reading one line and switches the color of the light source lit cyclically from one line to the next, an image sensor that reads one color per line, a data generation section that generates image data of the light source color which is the color of the light source lit during reading, a memory that stores a plurality of lines' worth of the image data, and a remaining color component generation section that determines the pixel value of a color component other than the light source color based on the pixel values of pixels around a pixel of interest.