1. A calibration target detection apparatus comprising: a light measurement region setting unit for setting a long light measurement region; a detection unit for detecting light measurement information of the light measurement region with a photometer provided to an onboard camera; a profile generation unit for generating a first profile, wherein the long light measurement region taking a predetermined one direction as a long direction is scanned along the other direction orthogonal to the one direction, and the change in the light measurement information in the other direction is shown; and a second profile, wherein the long light measurement region taking the other direction as the long direction is scanned along the one direction, and the change in the light measurement information in the one direction is shown; and a position calculation unit for calculating, on the basis of a characteristic point of the first and second profiles, a position of a calibration target or a position of a predetermined location of the calibration target, the calibration target being used for calibrating the onboard camera, and the calibration target being included in a captured image acquired by the onboard camera.