To provide a combustion system wherein ash produced by combustion of ligneous pellets can be efficiently scraped off a fire grate, and stably discharged into an ash recovery container.

An ash disposing means 13 is provided with a plurality of ash scraping members 23 attached to a frame body 26c surrounding the fire grate 26 of a burner part (a combustion part), an ash disposal box 24 attached to a lower end of the frame body, and the same number of auxiliary scraping members 25 attached to the box. The ash scraping member is comprised by axially providing a plurality of blades 23b having uneven parts on an outer circumferential face, it is orthogonal to a slit plate 23a of the fire grate, the blades are inserted in slits 23b, and they are exposed from the top and bottom. The auxiliary ash scraping member is comprised by circumferentially providing a plurality of vanes 25b extending in an axial direction, the vanes engages with the blades 23b, and the member 25 is rotated along with the member 23. The ash on the fire grate is scraped off by rotation of the member 23, the ash is forcibly transferred to discharge opening 24f of a bottom face part of the box 24 by rotation of the member 25, and the ash is discharged into the ash recovery container 14 below.