An exhaust gas purifying apparatus of an engine comprising: a reducing agent supply unit which is provided in an exhaust passage of the engine having a turbocharger, and which supplies a reducing agent into the exhaust passage; an exhaust gas purifying catalyst which is provided in the exhaust passage on a downstream side of the reducing agent supply unit, and which reduces and purifies nitrogen oxide contained in an exhaust gas in the exhaust passage by the reducing agent supplied from the reducing agent supply unit; a reducing agent supply control unit which controls operation of the reducing agent supply unit; a filter which is provided in the exhaust passage closer to a downstream side than a turbine of the turbocharger, which includes the reducing agent supply unit between the filter and the exhaust gas purifying catalyst, and which collects and burns particulate matter mainly composed of graphite contained in the exhaust gas; and an exhaust gas recirculation passage which introduces the exhaust gas from the exhaust passage between the filter and a supply position of the reducing agent from the reducing agent supply unit and recirculates the exhaust gas between a throttle valve of an intake passage of the engine and a compressor of the turbocharger and an opening and closing unit which opens and closes the exhaust gas recirculation passage based on the operating state of the engine, characterized by further comprising a reducing agent supply regulating unit which stops supply of the reducing agent from the reducing agent supply unit in an operating state of the engine where an exhaust gas introduction section of the exhaust gas recirculation passage is under a negative pressure when the opening and closing unit switches from a closed state to an open state and the exhaust gas flows back when the exhaust gas is recirculated through the exhaust gas recirculation passage. a reducing agent supply unit which is provided in an exhaust passage of the engine having a turbocharger, and which supplies a reducing agent into the exhaust passage; an exhaust gas purifying catalyst which is provided in the exhaust passage on a downstream side of the reducing agent supply unit, and which reduces and purifies nitrogen oxide contained in an exhaust gas in the exhaust passage by the reducing agent supplied from the reducing agent supply unit; a reducing agent supply control unit which controls operation of the reducing agent supply unit; a filter which is provided in the exhaust passage closer to a downstream side than a turbine of the turbocharger, which includes the reducing agent supply unit between the filter and the exhaust gas purifying catalyst, and which collects and burns particulate matter mainly composed of graphite contained in the exhaust gas; and an exhaust gas recirculation passage which introduces the exhaust gas from the exhaust passage between the filter and a supply position of the reducing agent from the reducing agent supply unit and recirculates the exhaust gas between a throttle valve of an intake passage of the engine and a compressor of the turbocharger and an opening and closing unit which opens and closes the exhaust gas recirculation passage based on the operating state of the engine, characterized by further comprising a reducing agent supply regulating unit which stops supply of the reducing agent from the reducing agent supply unit in an operating state of the engine where an exhaust gas introduction section of the exhaust gas recirculation passage is under a negative pressure when the opening and closing unit switches from a closed state to an open state and the exhaust gas flows back when the exhaust gas is recirculated through the exhaust gas recirculation passage.