1. A digital photographing apparatus that applies a high-speed multi-autofocusing (AF) method, the digital photographing apparatus comprising: a photographing lens; an image pickup unit configured to convert image light obtained from a subject through the photographing lens into an electrical signal to generate an image signal; a driving unit configured to drive a focus lens of the photographing lens; a calculation unit configured to calculate an AF evaluation value by performing AF on the image signal; a multi-AF detection unit configured to detect a peak of an AF evaluation value of each multi-point into which a captured image formed by the image signal is divided; a scanning unit configured to scan respective peaks of the multi-points of the captured image; a region detection unit configured to determine a zone where it is determined whether there is a possibility that a peak of AF evaluation values exists during scanning around a final end in the near direction or a final end in the ∞ direction by the scanning unit, and configured to invert a driving direction of the focus lens at a zone detection point before the final end of a scanning range in the near direction or the ∞ direction in response to the determination of the zone and to continue further scanning in the zone, wherein the possibility is determined according to whether the AF evaluation values monotonically increase or monotonically decrease at each lens synchronization position; and a main subject determination unit configured to select one of the peaks detected by the scanning unit according to a predetermined multi-AF method and determine a subject corresponding to the selected peak as a main subject, and perform contrast AF on the main subject.