PURPOSE: To obtain a high-quality gas with high efficiency, by feeding a high- temp. combustible gas produced in a waste treating a high-temp. combustible gas produced in a waste treating apparatus into the bottom of a vertical combustible gas reforming apparatus packed with a granular coke at the upper part of the bed equipped with a heat source.

CONSTITUTION: A waste is stored on a roaster 30 provided within a vertical waste treating apparatus. Air is fed via primary and secondary gasifying air inlets 10, 5 while a fuel 9 is burnt with a burner 4 for gasification. The generated high-temp. combustible gas is fed to the bottom of a vertical combustible gas-refoming apparatus 15 via an outlet 6 and a duct 8. Carbon, tar, etc. contained in the gas are oxidized with the air fed through a nozzle 18 of an air pipe 16, and the gas is brought into contact with a granular coke 14 placed on a bed 13 preheated with a heater 12 to allow it to reduce, fed to a gas cooling tower 19 via an outlet 17 to allow it to rapidly cool, fed into a scrubbing tower 20, where it is scrubbed with an alkali to absorb and remove hydrogen chloride, SO2 gas, etc., and taken out of the system via an outlet pipe 21.