In a conventional switch circuit capable of bidirectional conductivity, there is the problem that latch-up occurs in a parasitic thyristor included in a transistor having a switching function. Therefore it is an object of the present invention to provide a switch circuit capable of bidirectional conductivity while suppressing the occurrence of latch-up due to a parasitic thyristor. The present invention provides a switch circuit that includes diodes connected in parallel with each of a MOS transistor having the switching function and parasitic diodes present at the source and the drain of the MOS transistor.