Abstract: In an air-fuel ratio control with a learning control, a first correction values stored in a memory in correspondence to intake condition of a combustion engine and fuel injection time are renewed in response to an air-fuel ratio of mixture sensed in an exhaust of the combustion engine and a second correction value also stored in the memory is renewed in dependence on a difference between the first correction values stored in correspondence to the same intake condition. The first correction values are used to correct a basic fuel injection time determined by the operating condition, while the second correction value is used to correct an ineffective fuel injection time. Fuel is injected for an interval which is a sum of the corrected basic fuel injection time and the corrected ineffective fuel injection time.