PURPOSE: To switch a high frequency and high power with simple circuit constitution without using a load source device by switching a capacitor so as to discharge a stored electric charge of a PIN diode.

CONSTITUTION: When a control signal is inputted to an input terminal 8 in connecting an antenna terminal 1 and a receiver terminal 3, a bias given to the PIN diode 5 from a bias generating circuit 6 is lost. Since one end of a discharge capacitor 13a discharge capacitor 13 is grounded and the electric charge stored in the capacitor 13 is in opposite polarity with that of the electric charge stored in the PIN diode 5, the electric charge of the PIN diode 5 is discharged by the discharge capacitor 13, the PIN diode 5 is turned off (open) and the antenna terminal 1 and the receiver terminal 3 are connected.