PURPOSE: To control an air/fuel ratio so as to constantly be a theoretical air/fuel ratio in a process where an evaporated fuel of an internal combustion engine is emitted to a suction system by controlling the amount of evaporated fuel emission according to the correction amount due to the purging of fuel injection amount.

CONSTITUTION: A fuel injection amount to be supplied to an internal combustion engine M1 is calculated by a calculation means M4 according to a detection signal of a detection means M2 for detecting a driving condition of the internal combustion engine M1, while an air/fuel ratio feedback correction coefficient is varied so as to define the air/fuel ratio of an intake mixed air as a theoretical air/fuel ratio according to the detection signal of the detection means M2, and the fuel injection amount calculated by the calculation means M4 is corrected, by a first injection amount correction means M5. The fuel injection amount calculated by the calculation means M4 is corrected according to the evaporated fuel concentration obtained from the air/fuel ratio feedback correction coefficient by a second injection amount correction means M6, while the emission amount of the evaporated fuel emitted by a purging means M3 is corrected according to the evaporated fuel concentration as well as to the correction amount by the second correction means M6, by a purging correction means M7.