In method and apparatus for estimating an inter-vehicle distance of an automotive vehicle to a preceding vehicle which is running ahead of the vehicle, the inter-vehicle distance is detected using a radar, a video image of a vehicular forwarding zone is photographed, a plurality of edges including at least a part of the preceding vehicle are detected from the photographed vide image, an inter-edge spacing of mutually opposing edges from the detected image is detected, and a present inter-vehicle distance of the vehicle to the preceding vehicle at a present time point is calculated from a previous inter-vehicle distance calculated thereby at a previous time point at which the inter-edge spacing of the mutually opposing edges has previously been detected and the inter-edge spacings at the previous time point and at the present time point.