An exhaust gas recirculation device for an internal combustion engine having an intake air charging unit, comprising: an intake air passage that intakes intake air for the internal combustion engine; an exhaust passage that carries away exhaust gas from the internal combustion engine; an exhaust gas recirculation passage connected to the intake air passage; an exhaust gas recirculation valve interposed within the exhaust gas recirculation passage; and an intake air charging unit comprising: a compressor disposed in the intake air passage; a turbine disposed in the exhaust passage; wherein the exhaust gas recirculation passage recirculates a part of the exhaust gas based on an openness of the exhaust gas recirculation valve to control an amount of exhaust recirculation introduced into the intake air passage, wherein a first end of the exhaust gas recirculation passage is connected to the intake air passage upstream of the compressor of the intake air charging unit, wherein a second end of the exhaust gas recirculation passage is connected to the exhaust passage downstream of the turbine of the intake air charging unit, wherein the exhaust gas recirculation device further comprises: an intake air detecting means for detecting an amount of the intake air upstream of the compressor; an intake air pressure estimating means for estimating an intake air pressure in a position in which the first end of the exhaust recirculation passage is connected based on the detected amount of the intake air; a first exhaust gas pressure calculating means for calculating a first estimate of exhaust gas pressure in a position in which the second end of exhaust gas recirculation passage is connected based on the detected amount of the intake air; and a second exhaust gas pressure calculating means for calculating a second estimate of exhaust gas pressure by applying a predetermined response-delay processing on the first estimate of exhaust gas pressure, and wherein the opening of the exhaust gas recirculation valve is adjusted based on a second pressure difference between the estimated intake air pressure and the second estimate of the exhaust gas pressure. an intake air passage that intakes intake air for the internal combustion engine; an exhaust passage that carries away exhaust gas from the internal combustion engine; an exhaust gas recirculation passage connected to the intake air passage; an exhaust gas recirculation valve interposed within the exhaust gas recirculation passage; and an intake air charging unit comprising: a compressor disposed in the intake air passage; a turbine disposed in the exhaust passage; wherein the exhaust gas recirculation passage recirculates a part of the exhaust gas based on an openness of the exhaust gas recirculation valve to control an amount of exhaust recirculation introduced into the intake air passage, wherein a first end of the exhaust gas recirculation passage is connected to the intake air passage upstream of the compressor of the intake air charging unit, wherein a second end of the exhaust gas recirculation passage is connected to the exhaust passage downstream of the turbine of the intake air charging unit, wherein the exhaust gas recirculation device further comprises: an intake air detecting means for detecting an amount of the intake air upstream of the compressor; an intake air pressure estimating means for estimating an intake air pressure in a position in which the first end of the exhaust recirculation passage is connected based on the detected amount of the intake air; a first exhaust gas pressure calculating means for calculating a first estimate of exhaust gas pressure in a position in which the second end of exhaust gas recirculation passage is connected based on the detected amount of the intake air; and a second exhaust gas pressure calculating means for calculating a second estimate of exhaust gas pressure by applying a predetermined response-delay processing on the first estimate of exhaust gas pressure, and wherein the opening of the exhaust gas recirculation valve is adjusted based on a second pressure difference between the estimated intake air pressure and the second estimate of the exhaust gas pressure. a compressor disposed in the intake air passage; a turbine disposed in the exhaust passage; an intake air detecting means for detecting an amount of the intake air upstream of the compressor; an intake air pressure estimating means for estimating an intake air pressure in a position in which the first end of the exhaust recirculation passage is connected based on the detected amount of the intake air; a first exhaust gas pressure calculating means for calculating a first estimate of exhaust gas pressure in a position in which the second end of exhaust gas recirculation passage is connected based on the detected amount of the intake air; and a second exhaust gas pressure calculating means for calculating a second estimate of exhaust gas pressure by applying a predetermined response-delay processing on the first estimate of exhaust gas pressure, and