1. An information processing apparatus comprising: an image acquiring unit to acquire captured image given by capturing an image of a watching target person whose behavior is watched and an image of a target object serving as a reference for a behavior of the watching target person, the captured image containing depth information indicating depths obtained on a pixel-by-pixel basis within the captured image; a foreground area extracting unit to extract a foreground area of the captured image on the basis of a difference between a foreground image and the captured image, the foreground image being set to contain a depth of the foreground as the foreground of the captured image; and a behavior presuming unit to presume the behavior of the watching target person with respect to the target object by determining whether a positional relationship between the foreground area and the area of the target object in a real space satisfies a predetermined condition or not on the basis of referring to the depths of the pixels within the foreground area on the basis of the depth information, the predetermined condition being set on the assumption that the extracted foreground area is related to the behavior of the watching target person.