An image forming apparatus includes an irradiation unit for irradiating an image carrier having a detection image with light; a light-receiving unit for receiving reflected light of the light irradiated by the irradiation unit and outputting a detection signal corresponding to a light-receiving amount of the reflected light including a specular-reflected light component; and a detection unit for detecting one of position information and density information of the detection image based on a signal corresponding to a difference between a value of the detection signal corresponding to the light-receiving amount of the reflected light from a first position where the detection image is formed and a value of the detection signal corresponding to the light-receiving amount of the reflected light from a second position different from the first position.