A measuring system for easily detecting Misjudged Detection (M/D). A camera for measurement attached to a robot is used to obtain an image for measurement of a workpiece so as to measure and detect a set point. Next, a camera for validation is used to obtain an image for validation of the workpiece so as to measure and detect the set point. One camera may capture both of the images for measurement and validation, by utilizing movement of the robot. It is judged whether the measured results obtained from the images represent the same point on the workpiece or not. If yes, the measured results are judged to be valid, otherwise, the measured results are judged to be invalid and an exception process, such as a retrial, is executed. The images by the camera may also be used for judging a moving path of the robot during measurement of a large object.