An image forming apparatus including: a movable intermediate transfer member onto which a toner image borne by an image bearing member is to be transferred; a detection unit configured to irradiate the toner image on the intermediate transfer member with light to detect reflected light; and a control unit configured to adjust a condition for forming the toner image based on a detection result of the detection unit, wherein a plurality of grooves extending along a movement direction of the intermediate transfer member are formed in a surface of the intermediate transfer member in a width direction intersecting the movement direction, and wherein grooves, formed within a range of the intermediate transfer member to which the light is irradiated by the detection unit, among the plurality of grooves are formed so that intervals each between adjacent grooves with respect to the width direction are regularly changed within a predetermined range.