A combustion type waste gas treatment system capable of oxidatively decomposing a hazardous and combustible waste gas under heating efficiently with a structure which allows the waste gas to mix with an auxiliary burning gas efficiently without the occurrence of backfire in a waste gas inlet pipe. The combustion type waste gas treatment system has a burner part and a combustion chamber. Combustion flames are formed to extend from the burner part toward the combustion chamber, and a combustible waste gas is introduced into the combustion frames from waste gas inlet pipes thereby oxidatively decomposing the waste gas. A flow velocity accelerating device makes the flow velocity of the combustible waste gas flowing through the waste gas inlet pipe higher than the burning velocity of the combustible waste gas. <IMAGE>
