The combustion device for supplying air by a ventilator (22) can be reduced noise for combustion of high electrical-load effectively. The facing surface and distance of the device is for equivalent surface with the half-wave length of noise from 800 HZ to 3200 HZ and which includes each non-parallel surface in opposition to the facing surface at the inner sides of casing (24), nonparallel surface in opposition to the opposite surface for the surface of inner mix-case (21). A opposite surface for the burner plate (12) including non-parallel surface in opposition to the plate.
