A reading device includes an antenna having a signal radiating surface and configured to output a linearly polarized wave from the radiating surface, a movable and rotatable stage supporting the antenna and configured to move the antenna along a first direction parallel to the radiating surface of the antenna and rotate the antenna on an axis that is normal to the radiating surface of the antenna, and a tag reader connected to the antenna and configured to supply signals to the antenna for reading information from a wireless tag and to receive signals from the antenna including information read from the wireless tag.