According to one embodiment, an information processing device includes a position detecting section configured to detect a position of a hand from an input image of the hand, a memory section configured to store data of the position of the hand detected by the position detecting section, a rotation judging section configured to judge, assuming that records of the data of the position of the hand stored in the memory section show a rotary movement, that a latest position of the hand falls in an angle range predicted for the rotary movement, and an executing section configured to, when the rotation judging section judges that the latest position of the hand falls in the angle range, obtain a rotational angle at the latest position of the hand and also execute a process that corresponds to a predetermined rotary movement of the hand.