The invention relates to an incineration boiler for generating hot water or hot air by incinerating solid fuel composed of waste plastic, paper, wood, waste tire chips and the like. The incineration boiler includes a main body having a combustion space and a boiler space respectively on an inner lower side and an upper side, a solid fuel supply pipe disposed on a lower side of the main body in a cut-through manner, a burner on a lower side of the main body in a cut-through manner,a first air supply pipe on a lower side of the main body in a cut-through manner,to supply air compressed by the blower to the solid fuel in an eddy form, a vane rotatably disposed on an inner bottom of the main body and stirring the solid fuel in a specific direction, a water tank surrounding the combustion space in the main body and the boiler space and containing specific amount of water therein; a water pipe disposed on an upper inner side of the main body, the bottom of the water pipe being connected with the water tank; a water vapor separator disposed on the upper side of the main body; and an exhaust pipe configured on one sid eof the upper part of the main body in a cut-through manner.