In an internal combustion engine (1), air is taken into a cylinder (5) from an intake passage (30) through an intake valve (15). The amount of air taken into the cylinder (5) is controlled to a target intake air amount by having an engine controller (31) operate an intake throttle (23) in accordance with an accelerator opening (APO), taking into account a predetermined response delay (T2). The engine controller (31) calculates a predicted value (Qc1) of the intake air amount on the basis of the accelerator opening (APO), and controls a fuel injector (21) to inject fuel in a target fuel injection amount (Ti) which corresponds to this predicted value (Qc1) at a predetermined timing. In so doing, an improvement is achieved in the degree of precision with which air-fuel ratio control is performed when the internal combustion engine (1) accelerates or decelerates.