A method and apparatus to auto focus are provided. A distance classifier to auto focus includes a distance-calculating module calculating a focal distance on the basis of blur levels of at least two images; a precise distance-calculating module calculating the exact distance to a subject when an image that is captured at the focal distance calculated by the distance-calculating module is out of focus; and a distance-calculation-correcting module correcting the distance-calculating module on the basis of the blur levels and the exact distance to the subject that is calculated by the precise distance-calculating module.