An apparatus, method, and medium for dividing regions by using feature points and a mobile robot cleaner using the same are provided. A method includes forming a grid map by using a plurality of grid points that are obtained by detecting distances of a mobile robot from obstacles; extracting feature points from the grid map; extracting candidate pairs of feature points, which are in the range of a region division element, from the feature points; extracting a final pair of feature points, which satisfies the requirements of the region division element, from the candidate pairs of feature points; forming a critical line by connecting the final pair of feature points; and forming a final region in accordance with the size relationship between regions formed of a closed curve which connects the critical line and the grid map.