A projector includes an alternately-current-driven light source and a liquid crystal light valve that modulates light output from the light source. The light source and the liquid crystal light valve are driven under a condition that a current drive signal of the light source and a vertical synchronizing signal of the liquid crystal light valve are synchronized, and a synchronization timing of the current drive signal and the vertical synchronizing signal is changed to a different synchronization timing based on accumulated operating time at intervals of each time or a plural times of activation or with the same synchronization timing.