Abstract: An injection molding machine providing a stationary and a movable mold plate, each supporting one mold half, a drive means for the movable mold plate to close the mold and a rear end piece constituting a thrust from the drive means at the closing of the mold. Damage to the sealing surfaces of the mold due to objects stuck between the mold halves is eliminated by preventing a closing pressure from being applied to the mold if an object is located between the sealing surfaces all with a high degree of sensitivity without jeopardizing the rigidity or operational reliability of the machine.