A mobile communication device includes an antenna element, a low-frequency blocking element, an isolation circuit, a first high-frequency blocking element and a second high-frequency blocking element. The antenna element converts a radio-frequency signal into an electromagnetic wave and includes a radiation portion and a parasitic portion. The parasitic portion and the radiation portion generate a first sensing signal and a second sensing signal in response to a proximity of an object. The low-frequency blocking element transmits the radio-frequency signal to the radiation portion. The isolation circuit is connected between the parasitic portion and a ground plane, and the isolation circuit blocks the first sensing signal and transmits the radio-frequency signal. The first high-frequency blocking element transmits the first sensing signal to a first sensing controller through a first metal line. The second high-frequency blocking element transmits the second sensing signal to a second sensing controller through a second metal line.