A defect inspection system which features the inspection of an object to be inspected by optically matching the lights from a standard subject and the inspected object, whereas, an image signal is formed by a monochrome television camera based upon, and by having a plurality of detection sections which output signals corresponding to the rate of changes of the image signal with respect to time, so that although all of the above mentioned detection sections output signals when the above mentioned standard subject and the inspected object match, when the above mentioned inspected object does not match the standard subject, some of the above mentioned detection sections shall output signals while the other detection sections shall not output signals by arrangements of the sensitivities of the above mentioned plurality of detection sections, so that a defect detection signal is output whenever some of the above mentioned detection sections output no signals.