PURPOSE: To improve accuracy of detecting intake air flow and accuracy of controlling air-fuel ratio, at the time of transient operation.

CONSTITUTION: A correction amount Qtc of intake air flow is obtained (in step S1, 2, 4) in accordance with a change amount ΔP of pressure in a supercharge chamber in an engine with a supercharger, to obtain (in step S13) an exceeding amount QtcCO, when a correction amount Qtc1 obtained in the preceding time exceeds a predetermined value QsLMT, added to the correction amount Qtc in this time to obtain Qtc1 (in step S5), and when this Qtc1 exceeds QsLMT, the correction amount is limited to QsLMT (in step S12) and also adding the exceeding amount QtcCO to the correction amount Qtc in the next time. The correction amount Qtc1 or QsLMT is subtracted from a detection value Qa to set an intake air flow Qs, and this value is used to set a basic fuel injection amount Tp average-processed. In this way, excessive correction by an intake pulsation is suppressed at transient time to improve accuracy of detecting an intake air flow and accuracy of controlling air-fuel ratio.