Multi-bit input data is divided into at least a first bit group and a second bit group, and each of first sub-decode circuits selects one selection target signal/voltage from selection target signal/voltage group in accordance with the first bit group. Then, one signal/voltage is selected according to the second bit group from the signals/voltages selected by the first sub-decode circuits, and is transmitted to an output signal line. Each of second sub-decode circuits is formed of a single train of series switches, and only one of the switch train is made conductive to transmit a finally selected signal/voltage to the output signal line.