1. A vehicle-type determination apparatus that determines a type of a vehicle based on an image of the vehicle captured, the vehicle-type determination apparatus comprising: a unit that extracts, from the image, a horizontal straight line and a side straight line forming a contour of a vehicle-type determination area of the vehicle; a unit that obtains an angle between the horizontal straight line and the side straight line; and a vehicle-type determining unit that determines the type of the vehicle based on the angle.