A pixel having a structure in which low voltage drive is possible is provided by a simple process. A digital image signal input from a source signal line is input to the pixel through a switching TFT. At this point, a voltage compensation circuit amplifies the voltage amplitude of the digital image signal or transforms the amplitude, and applies the result to a gate electrode of a driver TFT. On-off control of TFTs within the pixel can thus be performed normally even if the voltage of a power source for driving gate signal lines becomes lower.