PURPOSE: To enable dust to be ignited under a state of producing no smoke and further its configuration for combustion to be simplified.

CONSTITUTION: An incinerator is constructed such that a discharging cylinder 2 is projected from an upper end of a main body 1 of the incinerator, a rostle 5 is installed at a lower part of the main body 1 of the incinerator, its upper region is applied as a dust loading space and concurrently an inner surface of a circumferential wall of the main body 1 of the incinerator is provided with many air feeding ports 11 and 11 at a range extending from its lower end to a part near its upper end. An air feeding fan is arranged at an upstream end of an air feeding passage communicated with these air feeding ports 11 and 11. An inner cylinder part 21 cooperatively arranged at the lower end part of the discharging cylinder 2 to be communicated with it is provided. An outer circumference of the inner cylinder 21 and its lower side are enclosed by a cylindrical guiding cylinder 4 having a bottom part cooperatively arranged from a top wall 19 of the main body 1 of the incinerator so as to have a predetermined clearance. An upper part of the guiding cylinder 4 is applied as a porous plate 41 and at the same time other portions are formed by a plate having no opening.