The invention relates to a method of adjusting a monitor having a radar and a camera and correcting the positions and orientations of their detection areas based on intensity of reflected light from a target object. A single target having a specified pattern of bright and dark areas in placed in front of the monitor in the detection areas of the radar and the camera. The detection area of the radar is adjusted first based on measurements taken of the target by the radar and thereafter axial displacement of the detection area of the camera is determined a coordinate conversion parameter is obtained based on an image of the target taken by the camera.