In an image display device which employs pulse width modulation driving, a voltage which is less than a voltage supplied to signal lines is applied to pixel electrodes. Tones are displayed by shifting phases of waveforms of the signal lines and scanning lines, and polarities of pixels in a signal line direction are inverted alternately. This prevents increase in power consumption which is caused by pulse intervals which become too small at high tone levels, in addition to preventing change in tone level due to external factors such as temperature, or signal delays in a driver or wiring.