Disclosed is a method of controlling a robot cleaner. The control method includes acquiring an image of the robot cleaner and a surrounding area of the robot cleaner at a reference position, the robot cleaner having two markers spaced apart from each other by a given distance, extracting the two markers from the acquired image, defining a horizontal plane of an actual space in which the two markers are located, based on positions of the two markers displayed on the acquired image and an actual distance between the two markers, acquiring position information of the robot cleaner relative to the reference position, based on position information of the two markers in the horizontal plane, and controlling travel of the robot cleaner based on the position information of the robot cleaner relative to the reference position.