PURPOSE: To avoid indefinite output and to prevent a through-current from flowing between a power supply and ground by providing a latch circuit to an output terminal.

CONSTITUTION: When control input signals S1, S2 do not select input signals D1, D2, an output of an AND circuit F is set to close a 3rd switch circuit SW3 and an input of a 3rd inverter 13 is connected to an output of a 4th inverter 14. Thus, an output of the selector circuit is kept to be an output of the selector circuit just before the switches SW1, SW2 are both opened. Thus, indefinite output is avoided and a through-current flowing between a power supply and ground is prevented.