An auto-focusing method includes: setting a central point of area of interest according to a user's input to select a moving object to perform auto tracking of the moving object within an image; setting an auto focusing area encompassing the central point of area of interest, the auto focusing area in which an operation is performed for auto focusing; setting a tracking sub-window encompassing the auto focusing area, the tracking sub-window in which an operation is performed for auto tracking; and tracking, by the central point of area of interest according to the user's input, the auto focusing area and the tracking sub-window, the moving object while changing a position of the auto focusing area and updating a position of the tracking sub-window according to a movement of the moving object.