result the gray level voltage can be transmitted to the output terminal without causing a voltage shift in the gray level generation circuit 100 a reverse bias leakage current flowing from the n well to the p well in the p channel mos transistor 113 is also supplied from the backgate voltage control circuit 122 though the illustration thereof is herein omitted a semiconductor switch according to the second embodiment of the present invention is described with reference to fig4 the semiconductor switch of the second embodiment includes an analog switch circuit 211 a switch control circuit 220 and a gray level generation circuit 200 the switch control circuit 220 includes a timing control circuit 121 a backgate voltage control circuit 222 and a bias circuit 223 herein the timing control circuit 121 of the second embodiment has the same structure as that of the first embodiment thus the same components as those shown in fig1 and fig2 are denoted by the same reference numerals and the detailed descriptions thereof are herein omitted the gray level generation circuit 200 includes a p channel mos transistor m 2 a plurality of resistor elements r and a diode d 0 which are connected in series between the h side power supply and the l side power supply the backgate voltage control circuit 222 includes a p channel mos transistor m 1 a plurality of resistor elements r and a diode d 1 which are connected in series between the h.