To provide an analog switch circuit which is free from the production of noises that are produced when a switching transistor is changed-over.

The circuit is constituted of a first transistor Q1 comprising a switch circuit, a second transistor Q7 constituting a differential pair with the first one, a constant current circuit 70 for the first and the second transistors and a power source wiring 80 for supplying a voltage to the first and the second transistors. The first transistor Q1 is the switching one and the current of the power source wiring 80 is made to be fixed regardless of the state of the switching transistor Q1.