The electromagnetic wave reflecting device includes: a reflection panel that reflects a radio wave of a desired band selected from a frequency band between 1 GHz and 170 GHZ; and a frame that holds the reflection panel. The frame has a conductive portion. The reflection panel is held by the frame so that an edge of the reflection panel is not exposed to an outside of the frame. At least a part of the conductive portion of the frame is covered with a non-conductive protecting member or protective coating.