A light emitting element deteriorates with time. Therefore, a method for reducing a lighting time is suggested to obtain a long life light emitting element. However, when the proportion (duty ratio) that a lighting time occupies per one horizontal scan period is reduced, the apparent luminance is also lowered. According to the invention, a light emitting element is controlled so that a light emitting period 205 and a non-light emitting period 206 are switched alternately at least once during a sustain period 203 in synchronism with a control signal. Thus, instantaneous lighting time can be reduced enough to reduce the duty ratio while maintaining the apparent luminance.