<p>In order to have a radio wave transmission suppression unit (19) function effectively across the entire periphery, the cross-sectional shape of a storage space (11) which faces an opening and closing door (12) is configured as an ellipse, and a radio wave transmission suppression unit (19b) is positioned in such a manner that the gap between the inner peripheral surface of the storage space (11) and the entire periphery becomes approximately uniform.</p>
