1. An information processing apparatus comprising: a storage unit configured to store, as background model information, for each of a plurality of predetermined regions, feature amount information of a past acquired image and likelihood information indicating a probability that a subject is represented; an acquisition unit configured to acquire an image of an analysis object; an extraction unit configured to extract a feature amount from each region of the acquired image; a detection unit configured to detect a foreground region from the acquired image based on the likelihood information contained in the background model information and a result of comparing the feature amount extracted from the acquired image with the feature amount information contained in the background model information; a calculation unit configured to calculate, for each detected foreground region, a likelihood indicating a probability that the detected foreground region represents the subject, based on information prepared for the subject; and an update unit configured to update the likelihood information contained in the background model information with the calculated likelihood.