1. An information processing device, comprising: two touch sensors each including a detection surface for detecting a position of an object thereon, the two touch sensors being arranged to be opposed to each other; reference determination means for determining at least one of a reference point and a reference axis based on one or a plurality of positions detected by one touch sensor of the two touch sensors; and operation input determination means for evaluating a content detected by another touch sensor of the two touch sensors based on the at least one of the reference point and the reference axis, which is determined by the reference determination means, to determine a content of an operation input of a user.