An antenna element (115) of an antenna device has first and second root sections (117) and (118) and an intermediate section lying between the first and second root sections (117) and (118). A feed section (114) is provided in the first and second root sections (117) and (118). The first and second root sections (117) and (118) are arranged so as to surround the feed section (114), and are provided in a wind section (113). Tail end linear parts in the wind section (113) extend in respective opposite directions. At least one of the first and second root sections (117) and (118) has a wider width part, which is formed such that a portion that overlaps a feed line connected with the feed section (114) is larger in width than other portions. This makes it possible to realize high radiant gain and improve a VSWR characteristic for each radio wave.