An object detection apparatus comprises a detection unit configured to calculate a detection likelihood from each of the plurality of frame images obtained by an image obtaining unit, and to detect a target object from each of the frame images based on the detection likelihood; and a tracking unit configured to calculate a tracking likelihood of the target object from each of the plurality of frame images, and to track the target object over the plurality of frame images based on the tracking likelihood, wherein the detection unit detects the target object from the frame images obtained by the image obtaining unit based on the tracking likelihood of the target object that is calculated by the tracking unit from the frame images, and the detection likelihood of the target object that is calculated by the detection unit from the frame images.