An apparatus for incinerating a waste gas comprises a combustion furnace main body having a peripheral wall and a hearth and a plurality of flare burners disposed on the hearth. Each of the flare burners including a burner main body having a peripheral wall and a bottom wall, at least one of the walls of the burner main body being formed with air intakes, an inwardly projecting flange provided on an upper portion of the peripheral wall of the burner main body, gas-air mixture tubes downwardly extending through the flange and arranged at a given spacing, a waste gas main pipe disposed under the burner main body, waste gas branch pipes extending upward from the waste gas main pipe, and gas nozzles mounted on the upper ends of the waste gas branch pipes respectively and positioned at the lower ends of the gas-air mixture tubes. The waste gas forced out from the nozzles ascends the interior of the mixture tubes along with the surrounding air and the gas-air mixture jets out from the tubes. When the mixture is ignited and burned, the swirling air currents produced above the flange support the combustion.