<p>Provided is an economical combustion device capable of not generating clinkers and of being continuously operated for a long period of time even when the solid fuel contains incombustibles. Specifically provided is a combustion device (10) vertically disposed with a screw conveyor (12) for transferring solid fuel directly above to the center inside a furnace body having a vertical cylindrical outer wall (11). The outer wall (11) and a concentric cylindrical middle wall (14) are disposed above the screw conveyor (12), and circling combustion air is supplied from above, between the outer wall (11) and the middle wall (14). A guiding member (15) for forming the upper end of the solid fuel in the shape of a heap is disposed near the upper end of the casing tube (12a) of the screw conveyor (12). The abovementioned device does not have a fire grate, the upper-end surface section of the solid fuel is burned while supporting same on the screw conveyor (12), and the incineration ash falls towards the ash retaining unit (16) disposed below.</p>
