1. An information processing device comprising: a frame image acquiring section configured to acquire a plurality of frame images that include a subject region in which an image of a subject appears and are taken at timings different from each other; a subject partial region identifying section configured to identify, about each of the frame images, a plurality of subject partial regions that are each part of the subject region and are different from each other in a position in the subject region; a partial region feature identifying section configured to identify partial region features showing variation in an image feature of an image occupying the subject partial region on the basis of the image feature of the image occupying each of the subject partial regions associated with each other in each of the frame images; and a contact determining section configured to determine whether contact of an object with the subject is present or absent on the basis of a relationship among the partial region features each associated with a respective one of a plurality of the subject partial regions.