A control device for an internal combustion engine having a supercharger, comprising: a throttle valve disposed downstream of the supercharger; a calculation unit which, based on a pressure and a temperature of an upstream section between a site upstream of the throttle valve and a site downstream of the supercharger, calculates a change amount (δ) of an air amount (EcTHU) in the upstream section, and calculates a throttle passage air amount (EcTH) having passed through the throttle valve from a difference between an introduced air amount introduced into the supercharger and the change amount, a first pressure sensor for detecting the pressure of the upstream section, a temperature sensor for detecting a temperature of air flowing through the upstream section, and an air flow sensor for detecting the intake air amount flowing into the upstream section, and wherein the calculation unit calculates the change amount by use of the pressure and the temperature obtained by the first pressure sensor and the temperature sensor, and calculates the throttle passage air amount from the difference between the introduced air amount and the change amount, the control device being characterized in that when a series of calculations for computing is taken as one computation cycle, the calculation unit calculates in a current computation cycle (n) an intake air amount ((Ec(n)) from a downstream section located downstream of the throttle valve into a combustion chamber of the internal combustion engine, based on the throttle passage air amount (EcTH(n)) calculated in the current computation cycle (n) and an intake air amount (Ec(n-1)) which is the intake air amount found in the previous computation cycle (n-1). a throttle valve disposed downstream of the supercharger; a calculation unit which, based on a pressure and a temperature of an upstream section between a site upstream of the throttle valve and a site downstream of the supercharger, calculates a change amount (δ) of an air amount (EcTHU) in the upstream section, and calculates a throttle passage air amount (EcTH) having passed through the throttle valve from a difference between an introduced air amount introduced into the supercharger and the change amount, a first pressure sensor for detecting the pressure of the upstream section, a temperature sensor for detecting a temperature of air flowing through the upstream section, and an air flow sensor for detecting the intake air amount flowing into the upstream section, and wherein the calculation unit calculates the change amount by use of the pressure and the temperature obtained by the first pressure sensor and the temperature sensor, and calculates the throttle passage air amount from the difference between the introduced air amount and the change amount, the control device being characterized in that when a series of calculations for computing is taken as one computation cycle, the calculation unit calculates in a current computation cycle (n) an intake air amount ((Ec(n)) from a downstream section located downstream of the throttle valve into a combustion chamber of the internal combustion engine, based on the throttle passage air amount (EcTH(n)) calculated in the current computation cycle (n) and an intake air amount (Ec(n-1)) which is the intake air amount found in the previous computation cycle (n-1).