To remarkably raise heat recovery for practical use by completely burning solidified fuel made of self-combusting materials and obtaining a heat exchanging heat source.

A heat exchanging combustion device uses, as a fuel, pellets which are obtained by solidifying self-combusting vegetable materials. The combustion device is provided with a large-capacity heat exchanging chamber having negative pressure, a portion of which is turned into an atmosphere of high temperature combustion for suction, dry distillation and gasification of the fuel and for attainment of complete combustion reaction. Thus the fuel is converted into high temperature radiant heat rays, i.e., electromagnetic waves which are directly radiated onto a large heat exchanging wall to attain highly efficient heat exchange. A combustion means in a large combustion chamber performs dry distillation with a hot-bulb functional device, which is made of far-infrared ray radiant ceramics and is provided to the base portion, and supplies air, in a staggered manner, through a plurality of peripheral edges to induce a combustion pattern of a candle flame. In the case where a high pressure air film is formed, traversing obliquely with respect to the flow of flames, the air film reacts with the flames to form a barrier which encloses the flames therein. As a result, the temperature of the enclosed flames is raised to turn the flames into radiant heat rays, and thus the most highly efficient heat exchange is developed. In this way, the amount of heat which is peculiarly possessed by a fuel can be converted into electromagnetic waves of high heat exchanging capacity.