A high-frequency switch circuit is provided for switching a connection between a common transmission circuit and an antenna side circuit in a plurality of transmitting and receiving systems. The high-frequency switch includes a connection between the antenna side circuit and a reception circuit in one of the plurality of transmitting and receiving systems, and a connection between the antenna side circuit and a reception circuit in the other of the plurality of transmitting and receiving systems, the high-frequency switch circuit comprising a first diode, a second diode, and a distributed constant line, wherein a third diode is connected to the first and second diodes through the distributed constant line.