A small, lightweight radio wave lens antenna device is proposed in which freedom of selection of the installation place is high, which can be compactly installed e.g. on a wall surface, and in which restriction of installation space is relaxed. A hemispherical Luneberg lens 2 is mounted on a reflecting plate 1, antenna elements 4 are supported by a retainer 3, they are integrally combined, and a mounting portion 5 is provided for mounting the reflecting plate 1 to a installation portion such as a wall surface with the reflecting plate 1 substantially vertical. The reflecting plate 1 may have such a shape that an area other than the area for reflecting radio waves from directions in a predetermined range is removed, preferably in the shape of a fan. The hemispherical Luneberg lens 2 is mounted on the reflecting plate 1, offset toward the small arcuate edge 1b of the fan. Further, a support arm 9 straddling the lens 2 is provided in the antenna device having a hemispherical Luneberg lens 2 provided on the reflecting plate 1, antenna elements 4 are mounted on an arcuate element retaining portion 9a of the support arm 9 along the spherical surface of the lens 2 with an angle adjustor 15 for adjusting the elevation at intervals corresponding to the distances between geostationary satellites by means of mounting means 11. Thereafter, the support arm 9 is pivoted to a predetermined angular position so that the antenna elements can be comprehensively positioned.