To provide an incinerator which can be effectively utilized for igniting waste materials such as foamed resin product or daily life waste materials recovered from a market as waste materials having resin substances and other ignitable substances mixed to each other.

In a cylindrical combustion furnace where fuel is ignited at its hearth, an agitating vane 30 with a rotating center of a main body of the combustion furnace being applied as a rotating center O and rotated along the hearth is arranged near a furnace bottom part, wherein the agitating vane 30 is entirely curved from the rotating center O toward its extremity end 31. In addition, the agitating vane 30 is formed such that side edges 32, 33 in its longitudinal direction are shaped to have an accute angle together at their sectional shapes, and concurrently their inner sides are made vacant. Combustion air supplied to the vacant inner sides is injected out of many small holes formed at the agitating vane 30.