DISCHARGE LAMP LIGHTING DEVICE

PROBLEM TO BE SOLVED: To enhance the startability of a discharge lamp while reducing damage to electrodes to extend the life of the discharge lamp by allowing smooth shift from a glow discharge to an arc discharge of the discharge lamp after breakdown. SOLUTION: This discharge lamp lighting device includes a DC power supply E, a down converter 1 for controlling the power of the discharge lamp La, a smoothing capacitor C1 connected to the output of the down converter, a startability improving circuit 2 connected in series with the capacitor, and an igniter Ig. The startability improving circuit 2 comprises a diode D2, a resistance R1 and a switch means SW1 connected in parallel with one another and the timing of opening and closing of the switch means SW1 is controlled by a control means 3. The control means 3 switches the switch means SW1 from an open state to a closed state at predetermined timing from a reference point defined during a period after the supply of power until the discharge lamp La reaches a stable lighted state.