A rotation device according to an embodiment includes a first gear, a second gear, and an energizing part. The first gear includes a toothless part and is connected with a rotation driving source. The toothless part is obtained by cutting a part of continuous teeth of the first gear. The second gear is arranged to be able to be engaged with the first gear and is rotated, when engaged with the first gear, in a predetermined direction by a rotation of the rotation driving source in one direction. The energizing part energizes the second gear in a direction reverse to the predetermined direction when the second gear is in a free state in which an engagement of the second gear with the first gear is released by the toothless part.