A method for controlling an internal combustion engine, - including an air amount control unit (10, 18) which is capable of controlling an air amount in a cylinder, - the method comprising controlling, during a transient period in which an operation state is shifted from a first operation state in which an air-fuel ratio in a supercharged state becomes a predetermined lean air-fuel ratio to a second operation state in which the air-fuel ratio in a non-supercharged state becomes a theoretical air-fuel ratio richer than the lean air-fuel ratio, the air amount in the cylinder such that a torque overshoot does not occur to the internal combustion engine by reducing the air amount in the cylinder so as to be an air amount smaller than an air amount realizing the theoretical air-fuel ratio, - wherein: - the air amount control unit (10, 18) is a throttle valve provided in an intake passage, - during the transient period, a throttle opening degree of the throttle valve is controlled such that the intake pressure becomes lower than the exhaust pressure, - during the transient period, the throttle valve is controlled such that the throttle opening degree is varied toward a valve closing side further from a steady-time target throttle opening degree in the second operation state by a predetermined amount (ΔP), and thereafter becomes the steady-time target throttle opening degree in the second operation state, - the predetermined amount (ΔP) is set so as to be larger as a supercharging pressure in the first operation state is higher, and - the predetermined amount (ΔP) is set so as to be smaller as engine speed (Ne) of the internal combustion engine in the first operation state is higher. - including an air amount control unit (10, 18) which is capable of controlling an air amount in a cylinder, - the method comprising controlling, during a transient period in which an operation state is shifted from a first operation state in which an air-fuel ratio in a supercharged state becomes a predetermined lean air-fuel ratio to a second operation state in which the air-fuel ratio in a non-supercharged state becomes a theoretical air-fuel ratio richer than the lean air-fuel ratio, the air amount in the cylinder such that a torque overshoot does not occur to the internal combustion engine by reducing the air amount in the cylinder so as to be an air amount smaller than an air amount realizing the theoretical air-fuel ratio, - wherein: - the air amount control unit (10, 18) is a throttle valve provided in an intake passage, - during the transient period, a throttle opening degree of the throttle valve is controlled such that the intake pressure becomes lower than the exhaust pressure, - during the transient period, the throttle valve is controlled such that the throttle opening degree is varied toward a valve closing side further from a steady-time target throttle opening degree in the second operation state by a predetermined amount (ΔP), and thereafter becomes the steady-time target throttle opening degree in the second operation state, - the predetermined amount (ΔP) is set so as to be larger as a supercharging pressure in the first operation state is higher, and - the predetermined amount (ΔP) is set so as to be smaller as engine speed (Ne) of the internal combustion engine in the first operation state is higher. - the air amount control unit (10, 18) is a throttle valve provided in an intake passage, - during the transient period, a throttle opening degree of the throttle valve is controlled such that the intake pressure becomes lower than the exhaust pressure, - during the transient period, the throttle valve is controlled such that the throttle opening degree is varied toward a valve closing side further from a steady-time target throttle opening degree in the second operation state by a predetermined amount (ΔP), and thereafter becomes the steady-time target throttle opening degree in the second operation state, - the predetermined amount (ΔP) is set so as to be larger as a supercharging pressure in the first operation state is higher, and - the predetermined amount (ΔP) is set so as to be smaller as engine speed (Ne) of the internal combustion engine in the first operation state is higher.