An exhaust gas purification system comprising: a diesel particulate defuser which is connected to an exhaust pipe of a diesel engine and collects particulate matter contained in exhaust gas, an exhaust pipe injector for performing exhaust pipe injection, an exhaust gas temperature sensor for detecting the exhaust gas temperature of the diesel particulate defuser, and an engine control unit which increases the exhaust gas temperature by controlling the exhaust pipe injector to perform the exhaust pipe injection and performs automatic regeneration of the diesel particulate defuser when an amount of particulate matter in the diesel particulate defuser becomes equal to or greater than a predetermined amount, wherein the engine control unit determines a difference between the exhaust gas temperature detected by the exhaust gas temperature sensor and a target regeneration temperature, and performs proportional integral derivative control of an exhaust pipe injection amount based on the difference, characterized in that the engine control unit resets to zero an integral control term in the proportional integral derivative control, when a transition is made from traveling automatic regeneration to idle automatic regeneration conducted during a stop while the exhaust pipe injection amount is proportional integral derivative controlled based on the difference. a diesel particulate defuser which is connected to an exhaust pipe of a diesel engine and collects particulate matter contained in exhaust gas, an exhaust pipe injector for performing exhaust pipe injection, an exhaust gas temperature sensor for detecting the exhaust gas temperature of the diesel particulate defuser, and an engine control unit which increases the exhaust gas temperature by controlling the exhaust pipe injector to perform the exhaust pipe injection and performs automatic regeneration of the diesel particulate defuser when an amount of particulate matter in the diesel particulate defuser becomes equal to or greater than a predetermined amount, wherein the engine control unit determines a difference between the exhaust gas temperature detected by the exhaust gas temperature sensor and a target regeneration temperature, and performs proportional integral derivative control of an exhaust pipe injection amount based on the difference, characterized in that the engine control unit resets to zero an integral control term in the proportional integral derivative control, when a transition is made from traveling automatic regeneration to idle automatic regeneration conducted during a stop while the exhaust pipe injection amount is proportional integral derivative controlled based on the difference. an exhaust pipe injector for performing exhaust pipe injection, an exhaust gas temperature sensor for detecting the exhaust gas temperature of the diesel particulate defuser, and an engine control unit which increases the exhaust gas temperature by controlling the exhaust pipe injector to perform the exhaust pipe injection and performs automatic regeneration of the diesel particulate defuser when an amount of particulate matter in the diesel particulate defuser becomes equal to or greater than a predetermined amount, wherein the engine control unit determines a difference between the exhaust gas temperature detected by the exhaust gas temperature sensor and a target regeneration temperature, and performs proportional integral derivative control of an exhaust pipe injection amount based on the difference, characterized in that the engine control unit resets to zero an integral control term in the proportional integral derivative control, when a transition is made from traveling automatic regeneration to idle automatic regeneration conducted during a stop while the exhaust pipe injection amount is proportional integral derivative controlled based on the difference.