PURPOSE: To improve mass productivity and to prevent the occurrence of ther mal deformation during combustion, by a method wherein a combustion chamber is formed with a plurality of porous plates, and the porous plates are coupled with each other by a means of pins, each extended through a flange part formed by bending the end of the porous plate.

CONSTITUTION: Porous plates 14a and 14b, with which is flat combustion cham ber 16 is formed, are completely separated into plural pieces and are part consti tution excellent in mass productivity. In the porous plates 14a and 14b, both ends are bent externally of a combustion chamber to form flange parts 15a and 15b, and durability to an external force is extremely increased. Even during combustion, the porous plates 14a and 14b are supported, whereby, speed washers 18, mounted to both ends of the pin 13 for coupling, has an axial resil ient effect, and also absorb thermal expansion. Especially, since the pin 13 is positioned to a relatively low temperature part, there is almost no tempera ture gradient of the interior of the pin 13 with no thermal deformation of the combustion chamber 16, and excellent combustion characteristics are maintained.