An embodiment of the present invention includes: a tracking object image extracting section that extracts a tracking object image, which represents a tracking object, from an image captured by a monocular camera; a two-dimensional displacement calculating section that calculates, as actual movement amounts, amounts of inter-frame movement of the tracking object image; a two-dimensional plane projecting section that generates on a two-dimensional plane a projected image of a three-dimensional model, which represents in three dimensions a capturing object captured by the monocular camera; a small motion generating section that calculates, as estimated movement amounts, amounts of inter-frame movement of the projected image; and a three-dimensional displacement estimating section that estimates amounts of three-dimensional motion of the tracking object on the basis of the actual movement amounts and the estimated movement amounts.