A high pressure discharge lamp includes an outer tubular bulb whose inner space is exhausted to a vacuum; an arc tube contained in the outer tubular bulb; and a voltage reducing switching element for reducing a voltage applied to the arc tube. The voltage reducing switching element includes a heat sensitive switching element and a starting-voltage reducing element which are connected in series. During a period in which the heat sensitive switching element has a predetermined temperature or higher, the heat sensitive switching element is closed to electrically connect the arc tube and the voltage reducing switching element in parallel, so that the starting-voltage reducing element is operated. During a period in which the heat sensitive switching element has a temperature lower than the predetermined temperature, the heat sensitive switching element is opened so that the starting-voltage reducing element is not operated.