PURPOSE: To improve working efficiency as well as to prevent rejects by detecting, at the entrance of a material feeding path, the upper thickness of the front side of the material to be worked, and adapting the driving motor of a feeding device or pressing device to be controlled in rotation.

CONSTITUTION: A sample of materials to be worked is positioned with the front edge thereof below the detection roller 25 of a material feeding path A. A forward operation switch is actuated to drive a motor to lower a pressing frame 12. Thereby, the detection roller 25 is also lowered to come in contact with the material to be worked, upon which a thickness detecting switch LS-1 is actuated to stop the motor and an interval of the material feeding path A is set to the thickness of the material. Pressing force is regulated through an eccentric actuator by the regulation of timing to actuate the detection switch LS-1. By this constitution, the pressing device is allowed to operate within its elasticity range without any forced operation, whereby rejects can be prevented and efficiency can be improved.