Pipe shaping method

A pipe shaping method forms a narrow neck (52A,52B) at one end of a workpiece (W) in the form of an elliptical pipe having a cross sectional shape elongated in a predetermined elongating direction, with a roller (27). The pipe shaping method includes the following steps of: cutting the end of the workpiece into a shape having first and second projections and first and second recesses which are arranged alternately along a circumference of the end of the workpiece, the first and second recesses of the end of the workpiece being spaced apart from each other in the elongating direction, each of the first and second projections projecting in a longitudinal direction of the workpiece between the first and second recesses each recessed in the longitudinal direction; mounting the workpiece (W) to a pipe holder (33); disposing the roller around the workpiece; and reducing a cross sectional size of the end of the workpiece by applying a compressive force on the circumference of the end of the workpiece by making such a relative movement between the roller and the workpiece as to revolve the roller relatively around the workpiece, to move the roller relatively in the longitudinal direction of the workpiece, and to vary a distance between the roller and a revolution axis of relative revolution of the roller around the workpiece.