This invention can increase the focusing speed and quickly focus a camera to an object regardless of the position of the object within the field of the viewfinder. When the position of a main object falls within a range in which phase difference AF is impossible, the lens scan range of contrast AF is determined by referring to distance measurement information of phase difference AF near the main object or immediately preceding distance measurement information of phase difference AF. The scan range of contrast AF is narrowed to increase the focusing speed.