A liquid crystal display device provided with an audio signal processing function, which includes an audio signal processing circuit with a large S/N ratio and a small glitch is provided. The display device of the invention includes a resistor string D/A converter circuit whose dynamic range can be increased by using a common power supply for a D/A converter circuit and a signal line driver circuit. Accordingly, a glitch generated in the D/A converter circuit can be reduced relatively to an audio signal and an S/N ratio of the D/A converted signal can thus be increased.