PURPOSE: To facilitate the manufacture of a waveguide and to reduce the cost by presetting a sinter body inside a casting mold at the manufacturing process of a wave guide and integrally casting the sinter body to the pipe wall of the waveguide, flowing a molten metal into a casting mold thereafter.

CONSTITUTION: The both ends of a waveguide are closed with its one end part being at a transducer side and the other end part at a dummy side. This waveguide presets a sinter body 2 at the place equivalent to the end part of the waveguide at the dummy side in the manufacture process. A molten metal is then flowed in this casting mold to integrally cast the sinter body to the pipe wall 1 of the wave guide. In this way the manufacture of the wave guide is facilitated and the cost down can be achieved.