A power supply method of supplying a high-potential drive power voltage to a data line driver circuit which drives a plurality of data lines in a display panel which has a plurality of pixels and a plurality of scanning lines in addition to the data lines. An output from the data line driver circuit to the data lines is set to a high-impedance state, and a charge corresponding to a charge discharged from the data lines is accumulated in a parasitic capacitor of a power line of a regulator which outputs a drive power voltage to be supplied to the data line driver circuit, within a given period. After the period, a voltage generated by the charge accumulated in the parasitic capacitor is output to the power line, and a voltage generated by the regulator is supplied to the data line driver circuit as the high-potential drive power voltage for the data line driver circuit.