An antenna includes: a substrate on or in which an antenna element part having an open end, a signal line connected to the antenna element part, and a first ground conductor connected to the antenna element part are formed; and a printed wiring board in which a second ground conductor electrically connected to the first ground conductor is formed in a different layer from the first ground conductor, wherein the second ground conductor has a shield part that partially overlaps with the antenna element part including a connection part between the antenna element part and the signal line and a connection part between the antenna element part and the first ground conductor and does not overlap with the open end of the antenna element part when viewed from a normal direction of the printed wiring board.