In an impedance conversion circuit, since, in a low band, an absolute value of impedance of a primary side coil is smaller than an absolute value of impedance of a capacitor, a high-frequency signal in a low band propagates through a transformer. Thus, impedance matching of a high-frequency signal in a low band is performed by the transformer. Since, in a high band, the absolute value of the impedance of the capacitor is smaller than the absolute value of the impedance of the primary side coil, a high-frequency signal in a high band propagates through the capacitor. Thus, impedance matching of a high-frequency signal in a high band is performed in the capacitor. Accordingly, impedance matching between a high frequency circuit and an antenna element is performed in a wide frequency band.