The invention provides a discharge lamp driving device capable of maintaining stable discharge. The discharge lamp driving device includes: a discharge lamp driving unit which supplies drive power to a discharge lamp; and a control unit which controls the discharge lamp driving unit. The control unit is configured to execute a first driving in which first drive power is supplied to the discharge lamp and a second driving in which second drive power that is equal to or higher than the first drive power and equal to or lower than rated power of the discharge lamp is supplied to the discharge lamp. The control unit executes the second driving in a launching period of the discharge lamp, and adjusts a heat load applied to the discharge lamp in the second driving executed in the launching period, according to a degree of deterioration of the discharge lamp.