AIR-FUEL RATIO CONTROL DEVICE OF INTERNAL COMBUSTION ENGINE

An air-fuel ratio control apparatus for controlling an air-fuel ratio of a supplied air-fuel mixture of an internal combustion engine to a target air-fuel ratio by a feedback control in accordance with an output signal of an oxygen concentration sensor provided at an exhaust pipe of the internal combustion engine, in which a perturbation control for vibrating the air-fuel ratio periodically to a rich side and a lean side centering on the target air-fuel ratio is executed in accordance with the output signal of the oxygen concentration sensor in a predetermined high load and high rotation operating state of the internal combustion engine.