There is provided a calibrating apparatus for an on-board camera of a vehicle, which allows speedy, yet reliable decision of acceptance/rejection of calibration result, with a simple apparatus construction, without depending on or being influenced by the calibration environment. An image processing target region on which an image processing for detection of each calibration point in each one of calibration markers in a camera-captured image which is a projecting plane of a camera coordinate system is displayed as a region frame in the form of a graphic image, in superposition with the camera-captured image.