Provided is an image input device which includes a laser range finder and a camera, and is capable of automatically calibrating the laser range finder and the camera at an appropriate timing without using special equipment. The image input device includes the laser range finder which measures distance information of an object by using invisible light and the camera which measures color information of the object. In order to detect a calibration error between the laser range finder and the camera, an invisible light filter which blocks visible light and transmits invisible light is automatically attached to a lens of the camera by a switching operation between two kinds of lenses. By the camera to which the invisible light filter is being attached, a pattern of the invisible light projected onto the object from the laser range finder is photographed as a visible image. By the comparison between the thus obtained invisible light pattern image and a reference image, the calibration error between the laser range finder and the camera is calculated. When the calibration error exceeds a predetermined value, a relative position and a relative posture between the laser range finder and the camera are automatically calibrated by control of a platform or the like.