Waste matter can be efficiently carbonized by using exhaust heat within the system, thus reducing the amount of auxiliary fuel (fossil fuel) needed to a minimum. The carbonized products which are produced during the process are burned and gasified in a gasification furnace. Gas transformation is carried out within the furnace and at the same time decomposition of the tar in the pyrolysis gas is achieved by contact with the high temperature gas (more than 1,100 degrees C) which occurs within the furnace. After gas transformation, syngas is fed to the cooler and the burnt dust is removed from the syngas by means of a gas refining apparatus. Power generation is carried out by gas engine or diesel engine. The exhaust gas of 600 degrees C from the power generation unit is effectively used as a heat source for the carbonizer.