To provide an incinerator capable of suppressing the generation of harmful smoke by supplying sufficient air to a matter to be incinerated.

The incinerator 1 comprises an incinerator main body 2 which is charged with matters 70 to be incinerated, an air supply unit 4 for forcibly supplying air and an air supply box 6 connected to the air supply unit 4, provided in an upper part of the incinerator main body 2 and supplying air fed from the air supply unit 4 to the incinerator main body 2. The air supply box 6 is provided with an upper air supply hole 64 for substantially horizontally supplying air, a lower air supply hole 66 for supplying air slantwise downward to a hearth and a side air supply hole 62 for supplying air along the inner wall of the incinerator main body 2 from one side of the air supply box 6. Thus, the sufficient air can be supplied to the matters 70 to be incinerated and unburnt gas in the incinerator main body 2, so that incomplete combustion is not generated and the generation of the harmful smoke can be suppressed.