A switch circuit for switching the connection of the receiving or transmitting circuits of two communication systems to an antenna circuit, which comprises first and second switch means having two switching elements, the first switch means comprising a first inductance element between a port connected to the antenna circuit and a port connected to the second switch means; the second switch means comprising a second inductance element between a port connected to the first switch means and a port connected to a receiving circuit of a first communication system, and a transmission line constituting the first inductance element having a lower characteristic impedance than that of a transmission line constituting the second inductance element.