A detecting apparatus which detects a quantity of various kinds of vehicle motion without using materials arranged on a road surface. The detecting apparatus is provided on a vehicle. A marking mechanism provides a mark on a road surface, the marking mechanism provided on the vehicle. An imaging device takes images of the road surface including the mark at a predetermined time interval. A quantity of vehicle motion is calculated by detecting a change in a position of the mark during the predetermined time interval based on a plurality of the images.