Aspects of the invention can relate to a light source that includes a light source lamp and an arc-tube drive unit. The light source lamp can include an arc tube that emits light between a pair of electrodes, a reflector that reflects the light from the arc tube to a region to be illuminated, and an auxiliary mirror that reflects the light emitted from the arc tube to the region to be illuminated toward the reflector. The arc-tube drive unit can drive the arc tube with an alternating current so that, of the pair of electrodes of the arc tube, the brightness of a first luminescent point generated in the vicinity of a first electrode adjacent to the auxiliary mirror is lower than the brightness of a second luminescent point generated in the vicinity of a second electrode remote from the auxiliary mirror.