To reduce the occurrence of displacement in an air-fuel ratio due to uncontrollability due to purge to an intake passage for evaporated fuel and to suppress the occurrence of unevenness in an air-fuel ratio due to defective purge distribution between cylinders.

In an engine wherein feedback control of an air-fuel ratio is effected based on the output of an O2 and a control of purge to an intake passage for evaporated fuel, a purge factor is corrected by a high density correction value considering the surging limit of a vehicle and a purge decrease amount correction value considering the limit of feedback control of an air-fuel ratio. In this case, based on a ratio tratio between of an actual fuel injection amount to a demand fuel injection amount corresponding to a target air-fuel ratio, the limit of feedback control of an air-fuel ratio to a demand fuel injection amount corresponding to a target air-fuel ratio, the limit of feedback control of an air-fuel ratio is decided, and when reaching a threshold, a flag xpgaf is erected and a purge reduction amount correction value pgaf is gradually increased.