PURPOSE: To pile plates in multiple lines without moving pilers in multiple lines and also without any damage thereto by constructing a device in a way that the traveling of an endless belt is stopped corresponding to the position of a back gauge to be detected and the moving amount of the endless belt, and the electromagnet is demagnetized.

CONSTITUTION: A concentrated control unit 47 is respectively sent a signal with regard to the shearing motion of a shearing machine, a signal with regard to whether or not the sheared plate passes by a plate passing detection switch 37, a signal with regard to the rotational amount of a servomotor 19 by a rotary encoder 21 via a back position control unit 57 and a signal with regard to the rotational amount of a servomotor 31 by a rotary encoder 33. A device is constructed in a way that further a numetrical value signal with regard to the shearing length of a plate to be sheared is sent to the unit from an operational command panel 49, on the basis of these signals, control signals are sent to a belt conveyor control unit 51, an electromagnet control unit 53, a shearing control unit 55 and a back gauge position control unit 57 respectively.