A detection apparatus includes an image acquisition interface and a controller. The image acquisition interface acquires captured images from an imaging apparatus that is installed in a vehicle and captures images of an area surrounding the vehicle. The controller calculates, on the basis of the captured images, the distance from the imaging apparatus to a road edge in the width direction of the road on which the vehicle is traveling or to an obstacle on the road and determines, on the basis of the calculated distance and information on an outer dimension of the vehicle, whether travel on the road by other vehicles will be possible after the vehicle has parked on the road.