To provide a waste treatment system which is capable of simply conducting the neutralization of an acid component in exhaust gas at a low cost, and to provide an exhaust gas treatment method.

The waste treatment system 1 is provided with an incinerator 2 to incinerate waste, a dust collecting apparatus 4 to collect soot dust contained in the exhaust gas generated in the incinerator 2 and an exhaust gas passage 11 to send the exhaust gas from the incinerator 2 to the dust collecting apparatus 4. A neutralizing agent supply path 13 to supply the neutralizing agent for neutralizing the exhaust gas is connected with the exhaust gas passage 11 and further a steam supply path 26 to supply steam to the neutralizing agent is installed.