A projector that outputs a first image and a second image alternately, includes a discharge lamp driving section that supplies, to a discharge lamp, a drive current that drives the discharge lamp; a state detecting section that detects a deteriorating state of the discharge lamp; and a control section that controls the discharge lamp driving section, wherein the control section controls the discharge lamp driving section so that the absolute value of the drive current becomes relatively small in the first period and relatively large in the second period and, in the second period, the control section controls the discharge lamp driving section so that the discharge lamp driving section supplies an alternating current to the discharge lamp as the drive current and controls the discharge lamp driving section so that at least part of the frequency of the drive current is decreased with the progress of the deteriorating state.