PURPOSE: To prevent the closing of a slag hole as caused by a melt slag dropping through the slag hole of a burning chamber for burning a fuel containing ash such as coal and growing adhering to the underside of the slag hole and the scattering of the melt slag.

CONSTITUTION: In a slag discharger of a burning device with which a fuel containing ash such as coal is burned in a burning chamber 1 and a slag is discharged from a slag hole 4, a cooling water surface is provided with an area thereof larger than the slag hole 4 in proximity down to the underside of the slag hole 4 and the whole of a melt slag 13 dropping from the slag hole 4 is caused to enter the cooling water surface instantaneously to crush the melt slag 13 by heat impact.