<p>A round bender is disclosed. According to an embodiment of the present invention, the round bender has a plurality of bending roll units arranged along a process line between both bender frames to curvature form a forming beam of a straight tube. The bending roll units has each upper and lower bending roll to be rotated between both bender frames, and the forming beam passes through a gap between the upper and the lower bending roll to be curvature formed in a predetermined curvature. The round bender has a curvature variable bending roll unit enables the upper bending roll to be moved frontward and backward to change the radius of curvature with respect to a predetermined section of the forming beam corresponding to the gap between two lower bending rolls in the rearmost side of the process line.</p>
