To attain identical matching states at two resonance points and also to improve the matching state at two different frequencies by connecting RF signals to 1st and 2nd feeding points through switching and also controlling an impedance which is connected to one of both feeding points that remains in a non-contacted state.

Electrical length of a 1st feeder line 21 is set at about 1/2 wavelength of a 2nd frequency, and electrical length of a 3rd feeder line 22 is set such that the total electrical length of a 2nd radiation conductor 11 and a feeder line 22 is set at about 1/2 wavelength of a 1st frequency. When the RF signal is connected to a 1st feeding point 12 from the line 16, the impedance of the radiation conductor 11 when viewed from the feeding point 12 is almost infinite at the 1st frequency. When the RF signal is connected to a 2nd feeding point 13 from the line 16, the impedance of a 2nd feeding end 21 when viewed from the point 12 is infinite.