PURPOSE: To suppress the unstable combustion state of an engine caused by the decrease in the air-fuel ratio accompanying alcohol, evaporated in a clank chamber, being reduced by an intake system.

CONSTITUTION: An air-fuel ratio control means 61 operates the quantity of feedback control for bringing this air-fuel ratio close to the logical air-fuel ratio, based on the air-fuel ratio being detected with an O2 sensor 34, and outputs a pulse signal to an injector 20, based on this quantity of control. A timer 63 outputs an operation command signal during the specified period after the water temperature of an engine reaches the boiling point of methanol. During output of this operation command signal, a judgment inhibition means 65 inhibits the abnormality judgment by an abnormality judging means 62 and the stop operation of air-fuel feedback control based on the abnormality judgment by an abnormality judging means 62, and a control range enlarging means 66 enlarges the range where the quantity of feedback control is operated, and a fuel jet reduction means 67 compulsorily reduces the set quantity of jetted fuel by a specified quantity.