To provide an exhaust gas treating apparatus with which excessive gas pressure variation at the recovering/exhausting time of converter exhaust gas, is restrained and gas spouting and air sucking amounts are reduced and the gas recovering amount is increased, and a recovering method.

A gas recovering apparatus in the non-combustion gas recovering type exhaust gas treating apparatus, is provided with; a pressure detection unit 24 in a gas recovering duct 12; a sucking side gas pressure detection unit 18 of an induced blower 9; a temperature detection unit 19; a spouting side gas pressure detection unit 21; a gas temperature detection unit 22; a number of rotations detection unit 20 of the induced blower; a current value or a shaft power detection unit 23 of a motor 17 for driving the induced blower; and a dissipation pressure control damper 15 arranged in an atmosphere dissipation side duct 11. The exhausting period into the atmosphere of the generated gas at blowing time, controls the opening degree of the dissipation pressure control damper so that the exhausting into the atmosphere side becomes the same pressure as the pressure in the gas recovering duct and the converter generated gas recovering period controls the opening degree of the exhaust pressure control damper so as to become the predetermined opening degree according to the actual gas volume to restrain the variation of the gas pressure at the recovering/exhausting time of the converter exhaust gas.