1. An information processing device, comprising: outline extraction means for extracting an outline of a subject from a picked-up image of the subject; characteristic amount extraction means for extracting a characteristic amount, by extracting sample points from points making up the outline, for each of the sample points; estimation means for estimating a posture of a high degree of matching as a posture of the subject by calculating a degree of the characteristic amount extracted in the characteristic amount extraction means being matched with each of a plurality of characteristic amounts that are prepared in advance and represent predetermined postures different from each other; and determination means for determining accuracy of estimation by the estimation means using a matching cost when the estimation means carries out the estimation.