An object detection apparatus comprising: an extraction unit adapted to extract a feature amount for each of partial regions that constitute image data; a storage unit adapted to store, as a background feature amount for each of the partial regions, a feature amount extracted in advance from background image data and does not include the target object; a first determination unit adapted to determine whether or not the partial region is an object region including the target object by comparing a current feature amount extracted from the partial region with the background feature amount; a deciding unit adapted to decide a parameter for each of the partial regions based on a plurality of results of determination; and a second determination unit adapted to determine whether or not the partial region is the object region based on the parameter and the results of determination.