An antenna (10) includes: a first radiant element (3) and a second radiant element (4), which are connected to an antenna feeding point (2); a first branch part (5a), one end of which is connected to the first radiant element (3) at a position not corresponding to an end portion of the first radiant element (3); a second branch part (5b), one end of which is connected to the second radiant element (4) at a position not corresponding to an end portion of the second radiant element (4); and a connection element (7), which connects part of the first radiant element (3) and part of the second radiant element (4). A different end of the first branch part (5a) and a different end of the second branch part (5b) face each other and form a capacitor part. The capacitor part is positioned outside the area surrounded by the connection element (7), the first radiant element (3), and the second radiant element (4). Part of the first radiant element (3), part of the second radiant element (4), the first branch part (5a), the second branch part (5b), and the capacitor part form a split ring resonator (8).