An antenna-matching device includes a first antenna terminal that is connected to a first radiating element, a second antenna terminal that is connected to a second radiating element, power feeding terminals and that are connected to a power-feeding unit C, an antenna coupling circuit (coupling inductance element L) that is connected in series between the antenna terminals, and a matching unit B that is connected between the antenna terminals and the power feeding terminals. The coupling inductance element L and the matching unit are integrally provided in a substrate. The matching circuit B is connected in series with the signal lines and includes a first resonant circuit and a second resonant circuit that have different resonant frequencies from each other and are coupled with each other. The matching unit B is connected to a power-feeding circuit that includes an RF circuit.