1. A tracking object selection apparatus which selects a tracking object, said tracking object selection apparatus comprising: an object detection unit configured to detect a predetermined object in an input image; a tracking unit configured to track the object detected by said object detection unit and calculate a candidate tracking object region in which the tracking object is present; a synthesis unit configured to synthesize the input image and an image of the candidate tracking object region calculated by said tracking unit so that the image of the candidate tracking object region is disposed at a predetermined position in the input image; a display unit configured to display the input image in which the image of the candidate tracking object region is disposed at the predetermined position as a result of the synthesis by said synthesis unit; and a selection unit configured to select a tracking object in a predetermined process, wherein, when a user performs an operation on the image displayed on said display unit and disposed at the predetermined position in the input image as a result of the synthesis, said selection unit is configured to select, as the tracking object, the object detected in the image on which the operation has been performed.