A modulator includes a modulation circuit for generating modulation signals based on inputted luminance data and for outputting the modulation signals to a plurality of image display elements, each of which is driven by a potential difference between a selection potential applied within a predetermined time period by a selection circuit and the modulation signal. The modulation signal has a waveform which is a combination of a plurality of unit pulses, with the unit pulses having an identical width and n kinds of peak values A1 to An, with n being an integer greater than 1, and A1<. . .