The restart properties of a light source even under the condition of a hot restart is improved, and suppression of the danger of an insulation breakdown in an unintended area is achieved by a light source comprising a discharge lamp in which a pair of main discharge electrodes are located opposite a discharge space; an auxiliary electrode arranged such that it does not come into contact with the discharge space; a feed circuit that supplies a discharge current to the main discharge electrodes; and a starter that produces a high voltage between one of the main discharge electrodes and the auxiliary electrode, wherein, during a time interval during which the starter produces said high voltage, a high voltage is also applied to the main discharge electrodes at least during a portion of the time interval.