PURPOSE: To omit the operation of data inputting or setting by selecting the bending pattern, inputting the dimensions, etc., and automatically calculating the bending angle, etc., required for bending.

CONSTITUTION: When the bending pattern is selected by a bending pattern selecting means 13, the number of bending pattern is outputted to a bending pattern information storing means 14 of the next stage. The data on the number of bending processes and direction, etc., in a bending machine corresponding to the bending pattern number and the bending pattern number are outputted to a bending data arithmetic means 11. When the dimension is inputted from a dimension input means 9, it is inputted to the bending data arithmetic means 11 through a dimension storing means 10B. The diameter of reinforcing bar is selected by a bending material diameter selecting means 16, and inputted to the bending data arithmetic means 11 through a bending material diameter storing means. The dimension of each side, the bending angle, and the direction necessary for bending are automatically calculated by the bending data arithmetic means 11. Therefore, a working time is largely saved.