An intake air control apparatus of an engine includes an Intake manifold configured to guide intake air into a plurality of engine cylinders. A plurality of first intake air passages communicate with the cylinders. A plurality of second intake air passages are disposed in parallel with the first intake air passages and communicate with the cylinders. An Intake throttle shaft passes through the first intake air passages. An intake air throttle valve is disposed inside the first intake air passages, rotates with the Intake throttle shaft, and opens/closes the first intake air passage. A swirl throttle shaft passes though the second intake air passages. A swirl throttle valve is disposed inside the second intake air passages, rotates together with the swirl throttle shaft, and opens/closes the second intake air passages. An actuator rotates selectively the Intake throttle shaft and the swirl throttle shaft. A controller controls the actuator.