1. An image processing apparatus, comprising: an image converting section which converts a size of input image data; a scanning controlling section which stores the size-converted image data, performs a scanning process of moving a square region having a predetermined size in the size-converted image data, and successively extracts square region image data; an image memory which stores the square region image data which have been extracted by the scanning controlling section; and a face detection processing section which detects a face region from the extracted square region image data, wherein the image memory stores a plurality of entries of face candidate image data containing face regions of a plurality of face candidates, and wherein the face detection processing section performs a face determining process of determining whether or not the square region image data contain a face region, and wherein if a determined result of the face determining process denotes that the square region image data contain the face region, the face detection processing section performs an identity determining process of setting an identity determination frame of which a predetermined width in a horizontal direction and a predetermined width in a vertical direction are added to face candidate image data for a predetermined face candidate stored in the image memory and determining whether or not the square region image data are contained in the identity determination frame.