PURPOSE: To prevent the deformation of a plate shaped body and the damages of a bending device by operating the command data for a displacement mechanism and by moving the plate shaped body through the space between an upper die and lower die based on the command data thereof.

CONSTITUTION: The 1st arithmetic means operates the 1st data including the position information of the bending points P1, P2... of a plate-like body 300 and the discriminating means discriminates the size relation of the distance between mutually adjoining bending points P1, P2... and the prescribed length based on the 1st data. The 2nd arithmetic means operates the 2nd data including the position information concerning the prescribed points Q1, Q2... having the prescribed position relation for the set of the corresponding bending points and being given on each set of the bending points consisting of the bending points which are by the number selected according to the result of the discrimination. The command data operating means operates then a command data so that the prescribed points Q1, Q2... can pass in order the prescribed basic point based on the 2nd data and the displacement mechanism performs the movement of the plate-like body 300 based on the command data.