A focusing apparatus and method are provided for a digital image processing apparatus. The focusing apparatus and method control an image sensor to read only pixels within a preset region of an image, calculate a focus value using only the read pixels, and apply the focus value to the entire image. The focusing apparatus includes: a region setting unit setting an arbitrary focus region of an image; a set region pixel reading unit reading only pixels within the set focus region; a focus value calculating unit calculating a maximum focus value according to a moving distance of a focus lens for achieving an in-focus state with respect to the pixels within the focus region read by the set region pixel reading unit; and a control unit applying the calculated maximum focus value to the entire image.