PURPOSE: To make possible intake and exhaust intake and exhaust tubes by such a construction that the exhaust gas is jetted into the room by the use of a combustion fan and the exhaust gas in the room is released to outdoors by the use of a separately provided exhaust fan having a larger capacity than the combustion fan.

CONSTITUTION: When the combustor's body 1 is turned into operation an intake & exhaust fan 11 begins to rotate for normal operation. At this time, air for combustion is taken from the air in the room to be sucked through an incoming air receiver mouth 2 while the exhaust gas produced by the combustion is jetted into the room out of the exhaust nozzle 3, directed to the exhaust gas reveiver mouth 16 leading to the intake & exhaust part 4. At the same time, the air in the room is sucked through the exhaust gas receiver mouth 16 by the action of the intake & exhaust fan 11 and released to outdoors from the exhaust cylinder 10. Compared with a combustor of conventional forced intake & exhaust type, this can spare an intake tube and an exhaust tube to assure a greater installation margine and the extent where movement is allowed after installation, is also wider.