An antenna device that is placed adjacent to an antenna 5 for receiving a high frequency signal and includes an impedance matching circuit 6 and an amplifying circuit 21 to which a DC control voltage is supplied from a demodulating device 3 through a feeder cable 4 for transmitting the high frequency signal to the demodulating device 3, wherein the DC control voltage is set to a value for adjusting a frequency characteristic of the impedance matching circuit 6 within an allowable range corresponding to a received frequency. A small and inexpensive antenna device having a simple circuit configuration and good reception sensitivity is implemented.