Exhaust gas recirculation system

An exhaust gas recirculation system for an engine, comprising:

• an exhaust gas recirculation path for establishing communication between an exhaust path and an intake path of an engine and recirculating part of exhaust gas back into the intake path;
• exhaust gas flow rate detection means for detecting the rate of an exhaust gas flow in the exhaust recirculation path;
• an exhaust gas flow control valve for controlling the rate of an exhaust gas flow in the exhaust recirculation path;
• and
• a catalyst that is installed upstream of the exhaust gas flow rate detection means to purify soiling substances in the exhaust gas,
• wherein the operating status of the exhaust gas flow rate detection means is controlled while using a signal in accordance with the conditions of the catalyst as one input.