Structural characteristics have been analyzed for gear system in a commercial iron bending machine which is widely used at many building construction sites. This complicated gear system in the bending machine is fundamental power transfer unit from electrical motors, and it is composed of various configuration structure including various spur and helical gear assembly. Main structural characteristics of the gear system such as stress and deformation distributions are predicted with numerical simulation of FEM method for various operating conditions of torque and rotation speed. Results show that there is large deformation in lower region of driving gear, and high stress near those contact area which is greatly affected by motor torque. These results can be applied for the design improvement of efficient gear system in the iron bar bending machine.