A data signal voltage on a signal line is held in a voltage holding capacitor through an n-type MOS transistor switched on by a gate scan voltage, and supplied to an analog amplifier circuit. The analog amplifier circuit is formed of an MOS transistor having a double gate structure, and the operating point thereof is set at an operating range in which dependence of Ids on Vds is substantially nullified. Even when Vds is varied due to a response of liquid crystal, Ids is substantially fixed. Accordingly, the pixel voltage which is substantially proportional to the data signal voltage can be applied to the liquid crystal.