PURPOSE: To manufacture elbows from pipes without performing complicated development, cutting and welding, by applying a hydraulic pressure to the inside of pipes, by bending pipes by applying an axial pressure to pipes, and then, by adding an internal pressure produced by the further hydraulic pressure.

CONSTITUTION: A crude pipe 6 is inserted into the space between a top metal mold 7, pressure molds 8 and a bottom metal mold 9, and an axial pressure is applied to both ends of pipe 6 by advancing a pressure piston 10. Then, the pipe 6 is filled with oil supplied through a bulge pressure liquid supplying hole 11 and an air hole 11', and a bending rigidity is given to the pipe 6 itself by applying a high pressure. After the bending rigidity is given to the pipe 6, the metal mold 9 is raised and the pipe 6 is bent to become an elbow which has a prescribed shape. In this case, after the pressure molds 8 and 8' and bottom metal mold 9 are closely adhered to the top metal mold 7, the further high pressure of bulge pressure is added through bulge pressure liquid supplying hole 11 and the crude material 6 is closely adhered to the metal molds. In this way, a mass production of elbow can be performed easily.