PURPOSE: A change in the amount of the laser beam reflected from the surface to be broken is detected to control the position of the squeegee, thus increasing the glass breaking efficiency and breaking accuracy.

CONSTITUTION: A command from the controller causes the hydraulic unit to operate and the hydraulic cylinder 8 lowers the automatic pressing head 1. The squeegee 2 made of an elastic material, a tool for breaking glass, integrally moves together with the outside frame 20 of the head 1 until it comes into contact with the glass to be broken 3 on the top edge, but after contact, the glass to be broken is pressed by lowering down the outside frame with the aid of the cylinder 8. The position of the squeegee 2 is monitored with the displacement detecting sensor 6 and informed to the controller. As the squeegee increases the pressure, the glass begins to break from the scribe trace 4 to form the broken surface 28. A laser ray 15 is reflected at the surface 28 and, when the amount of the laser increases by the formation of the surface 8, the change is given to the output signal from the beam receiving element 15 to raise up the squeegee 2 instantly. Thus, excessive pressing to the glass 3 is prevented.