PURPOSE: To bend the plural sides of a stock to be worked consisting of various materials and having thickness by exact angle and dimensions.

CONSTITUTION: By a first and a second bending faces 18b, 19b of an upper die and a lower die 18, 19 which are divided, a first and a second bending parts can be subjected to bending in both sides of the stock W to be worked. A laminated spacer die 301' has a third and a fourth bending faces 301b, 302e having a prescribed angle against a first and a second bending faces 18b, 19b, and can furthermore execute the bending of a third and a fourth bending parts to the stock W. The laminated spacer die 301' is inserted automatically between the divided lower dies 18, 19 after being selected by the number of pieces corresponding to the interval by a selecting/positioning mechanism 300, and has a function for preventing the deformation of the lower dies 18, 19.