PURPOSE: To prevent the generation of switching noises by switching an MOS TR gate with a main switch configuration and back gate gradually in an electronic switch having a CMOS configuration.

CONSTITUTION: When the voltage of a node A of a control input terminal 6 is turned to the H level, MOS TRs 14, 15 are turned off and on respectively and a capacitor 16 is charged by a constant current source 13, so that the voltage of a node B is changed ascendingly. On the other hand, TRs 20, 21 are turned on and off respectively and a capacitor 22 is discharged by the constant current source, so that the voltage of a node C is changed descendingly. Consequently, the main switch consisting of TRs 1, 2 is turned from off to on gradually. If the voltage of the node B drops down to 0, node voltages D, E are changed and the node F of the back gate of the TR1 is switched from the node B side to the input terminal 4 side.