To provide a burring processing method using a forming head, capable of burring processing not only of a perfect circle shape, but of any prescribed opening shape such as an elliptical shape and a long hole or the like.

The burring processing method comprises to insert a forming head 2 in a prepared hole 1 which is bored in a work W, and to draw out the forming head 2 from the prepared hole 1 by rotating the forming head from side to side and making the forming head to contact the edge of the opening. The processing is carried out with the work W being moved in linear, horizontal and back-and-forth motion at a fixed stroke while the forming head 2 moves up and down.