To provide a combustion device capable of continuously burning solid fuel such as wood chips and wood waste for a long period while keeping high combustion efficiency.

An air flow channel 12 of an annular space is disposed between concentrically-disposed outer jacket cylindrical body 3 and intermediate cylindrical body 4 of a small diameter, an air blower 13 is disposed to supply the air toward the tangential direction of the outer jacket cylindrical body 3 and the intermediate cylindrical body 4 to the air flow channel 12, a flow guide section 3a for guiding the air toward an inner peripheral wall of the intermediate cylindrical body 4 is disposed on an upper end section of the air flow channel 12, a combustion cylindrical body 11 having a diameter and a cylinder height smaller than those of the intermediate cylindrical body 4, is concentrically disposed inside of the intermediate cylindrical body 4 at a lower position of the intermediate cylindrical body 4, an ash discharge passage 17 of an annular space is formed between the intermediate cylindrical body 4 and the combustion cylindrical body 11, a fuel supply cylinder 10 for solid fuel F is communicated and connected with a lower end opening of the combustion cylindrical body 11, and an ash collection box 18 for recovering the ash, is detachably disposed at a lower part of the ash discharge passage 17.