An image reading device includes: a reading unit in which light receiving elements are arranged in a line along a second direction; and a light source control section that controls emission of the light source members, the light source control section performing control such that light is emitted in a cycle order of the first, second, and third colors on the basis of a reference signal which is output at a preset time interval, and to make a time of emission of the light with the first color close to a time of start of emission of the light with the second color and to make a time of emission of the light with the third color close to a time of end of emission of the light with the second color.