An image reading device comprising: a light source section that shines light on a document along a line direction, that includes light sources (73R, 73G, 73R) of a plurality of colors, and that emits light in one color during a period for reading one line and switches a color of a light source (73R, 73G, 73R) lit cyclically from one line to the next; an image sensor that, based on light reflected from the document, reads one color per line; a data generation section that, based on an output of the image sensor, generates image data of a light source color which is the color of the light source (73R, 73G, 73R) lit during reading; a memory that stores a plurality of lines' worth of the image data generated by the data generation section; a remaining color component generation section that, by using the plurality of lines' worth of the image data stored in the memory, generates a pixel value of a color component other than the light source color based on pixel values of pixels around a pixel of interest; and. an edge processing section that recognizes whether or not the pixel of interest is an edge pixel, characterized in that the edge processing section extracts pixels that are located across, with the pixel of interest at a center, a total of five or more lines in a direction perpendicular to lines and that are read in the light source color, the edge processing section recognizing, when a previously determined condition is met, the pixel of interest to be a monochrome edge pixel and recognizing, when the previously determined condition is not met, the pixel of interest not to be a monochrome edge pixel; when the edge processing section recognizes the pixel of interest to be a monochrome edge pixel, the remaining color component generation section generates the pixel value of the color component other than the light source color of the pixel of interest such that it is a pixel value of the pixel of interest in the light source color, and when the edge processing section recognizes the pixel of interest not to be a monochrome edge pixel, the remaining color component generation section generates the pixel value of the color component other than the light source color of the pixel of interest such that it is a mid value between pixel values of interpolation target pixels, the interpolation target pixels being two pixels that sandwich the pixel of interest in a direction perpendicular to the line direction and of which the light source color is a color to be generated and the previously determined condition comprising a condition that, of the extracted pixels, two or less are inflection point pixels and a condition that no adjacent pixels are inflection point pixels. a light source section that shines light on a document along a line direction, that includes light sources (73R, 73G, 73R) of a plurality of colors, and that emits light in one color during a period for reading one line and switches a color of a light source (73R, 73G, 73R) lit cyclically from one line to the next; an image sensor that, based on light reflected from the document, reads one color per line; a data generation section that, based on an output of the image sensor, generates image data of a light source color which is the color of the light source (73R, 73G, 73R) lit during reading; a memory that stores a plurality of lines' worth of the image data generated by the data generation section; a remaining color component generation section that, by using the plurality of lines' worth of the image data stored in the memory, generates a pixel value of a color component other than the light source color based on pixel values of pixels around a pixel of interest; and. an edge processing section that recognizes whether or not the pixel of interest is an edge pixel, characterized in that the edge processing section extracts pixels that are located across, with the pixel of interest at a center, a total of five or more lines in a direction perpendicular to lines and that are read in the light source color, the edge processing section recognizing, when a previously determined condition is met, the pixel of interest to be a monochrome edge pixel and recognizing, when the previously determined condition is not met, the pixel of interest not to be a monochrome edge pixel; when the edge processing section recognizes the pixel of interest to be a monochrome edge pixel, the remaining color component generation section generates the pixel value of the color component other than the light source color of the pixel of interest such that it is a pixel value of the pixel of interest in the light source color, and when the edge processing section recognizes the pixel of interest not to be a monochrome edge pixel, the remaining color component generation section generates the pixel value of the color component other than the light source color of the pixel of interest such that it is a mid value between pixel values of interpolation target pixels, the interpolation target pixels being two pixels that sandwich the pixel of interest in a direction perpendicular to the line direction and of which the light source color is a color to be generated and the previously determined condition comprising a condition that, of the extracted pixels, two or less are inflection point pixels and a condition that no adjacent pixels are inflection point pixels.