A deceleration device according to an embodiment includes a driven gear configured to rotate about a rotational axis by driving power of a drive mechanism; a deceleration unit including a plurality of gears including a first gear and a second gear, the first gear that rotates by the driven gear, the second gear that rotates about the rotational axis, the deceleration unit configured to rotate the second gear at a reduced speed with respect to the driven gear; a first contact included in the second gear; and a second contact provided separately from the driven gear and the plurality of gears and configured to come into contact with the first contact to stop the rotation of the second gear.