A control device for an internal combustion engine capable of conducting lean burn control, such as exhaust gas emission control, always optimally regardless of a timewise change of the internal combustion engine, variations in engines, and an environmental change. The control device includes a detector for detecting a burn condition of the internal combustion engine, a lean limit air-fuel ratio factor map, a lean burn feedback logic, an oxygen concentration sensor, and a feedback control logic for controlling an air-fuel ratio to a theoretical air-fuel ratio, wherein lean burn is performed at the middle point between the lean limit air-fuel ratio and the theoretical air-fuel ratio.