Two high frequency antennas (6) are provided in a multilayer substrate (2). Each high frequency antenna (6) is configured of a radiation element (7), a high frequency power supply line (8), and a high frequency power supply unit (9). A low frequency antenna (10) is configured of a series radiation element (11), a low frequency power supply line (13'), and a lower frequency power supply unit (14). The series radiation element (11) is formed of two radiation elements (7) connected by a radiation element connection line (12). One end side of the series radiation element (11) is connected to the low frequency power supply unit (14) via the low frequency power supply line (13). Open stubs (15) to block transmission of a high frequency signal (SH) are connected to the radiation element connection line (12) and the low frequency power supply line (13). Short stubs (16) to block transmission of a low frequency signal (SL) are connected to the high frequency power supply lines (8).