A medium transportation apparatus is provided with a plurality of medium transportation units, a drive source, a sun gear connected to the drive source, a planetary gear engaging the sun gear for transmitting a drive force to one of the medium transportation units according to a rotational direction of the sun gear, and a rotational load member for applying a rotational load to the planetary gear. The rotational load member is disposed on an outer side relative to a rotational shaft of the planetary gear in a radial direction of a rotational shaft of the sun gear.