To provide a bending apparatus by a robot capable of performing the sophisticated bending with excellent accuracy so as to obtain a desired product in any case by detecting the deviation between the actual die position and the die position on the program, correcting a robot operational program if there occurs any deviation, and checking the position of a workpiece when the robot positions the workpiece, and a bending method thereof.

The bending order, the die layout, and the workpiece position are determined based on product information in advance. The actual die position is compared with the predetermined die layout. If there occurs any deviation between the two, a robot operational program is corrected. The actual workpiece position is compared with the predetermined workpiece position, and if there occurs any deviation between the two, the robot position is corrected, and a workpiece held by the robot at the corrected position is subjected to the bending.