PURPOSE: To obtain a solid substance burner having a simple structure and a high burning efficiency.

CONSTITUTION: A fuel supply port 3 and a cover 3a for closing the port 3 are provided at an upper part of a refractory brick vessel 1. A screw conveyor 7 for feeding ash toward a discharge port is mounted at the bottom of the vessel 1. Water 5 is stored in the bottom of the vessel 1. An air supply tube 11 extended from a blower 9 is horizontally fixed to an intermediate stage in the vessel 1. Many holes 11a are opened at a periphery of the tube 11, and its end is closed. A burner nozzle 13 is mounted at a vessel wall substantially at the same level as that of the tube 11 toward an exterior. The nozzle 13 communicates with the interior of the vessel 1.