A radio wave transparent cover is arranged in front of a radio wave radar device with a space in between in a radio wave emitting direction of the radio wave radar device such that radio waves emitted from the radio wave radar device pass through the inside of the radio wave transparent cover. A formation area, which includes the entire radio wave transparent area on the back side of the cover, is formed by an embossed uneven surface having an embossing depth of a range of 5 μm to 200 μm, inclusive.