Output voltages of R-2R ladder resistor type digital-to-analog conversion circuits are once stored in sample and hold capacitors through sample and hold charging amplifiers and the voltages stored in the capacitors are then supplied to a liquid crystal panel through panel drive amplifiers and multiplexers simultaneously. Power supplies to the digital-to-analog conversion circuits and the charging amplifiers are turned on by means of switches only during the period that the voltages are written in the capacitors and turned off during other periods. Two systems of the capacitors and the panel drive amplifiers are provided in order to make the operation of charging the analog voltages to the capacitors and the operation of taking out the analog voltages stored in the capacitors to supply the voltages to the liquid crystal panel in parallel.