PURPOSE: To reduce considerably a component of an output signal of a switch of a pre-stage from being leaked to an output terminal of a switch of a post- stage.

CONSTITUTION: A pre-stage switch 12 is made up of switch sections 21, 22 and a bias application switch 23 each comprising a semiconductor element and when a bias control switch 40 is closed, any of input terminals T1, T2 is connected to an output terminal T5. A post-stage switch 13 is made up of switch sections 31, 32 and a bias application switch 33 connects any of input terminals T3, T6 connecting to an output terminal T5 of the switch 12 to an output terminal T4. When the switch 13 selects the input terminal T3 with a control signal from a control terminal T12, a bias control switch 40 is open and since no bias current is supplied to the switch sections 21, 22 of the switch 12, the sections 21, 22 are made open.