PURPOSE: To accurately, automatically and efficiently inspect a carved stamp on a gold bullion independently of the size of the carved stamp by detecting the carved condition of the gold bullion immediately after carving it, inputting the detection result to a controller and executing the image processing of the inputted data.

CONSTITUTION: A camera 4 including an image sensor is fixed to the hand 3 of a robot 2, a carved stamp such as a company mark, quality and a production number is pressed to the upper surface of a gold plate body 5 by an automatic marking press 1, at the time of generating a carved stamp completion signal, the robot 2 is driven, the state of the carved stamp is detected by the camera 4 including the image sensor fixed to the hand 3 immediately before the hand 3 grasps the metal plate body, and the detected result is inputted to the controller 6. After processing the image, the processed input data is compared with data indicating the accurate carved stamp state of the gold plate body 5 which has been previously inputted to the controller 6 to inspect the validity of the carved stamp. Consequently, the validity of the carved stamp can be accurately, automatically and efficiently can be inspected immediately after pressing the carved stamp to the gold bullion in a stable state for a long time independently of the size of the carved stamp.