A discharge lamp operating device having a high frequency inverter is discharged. Connected to a secondary winding of an oscillation transformer of the high frequency inverter is a discharge current supply circuit having a switch for controlling supply of a discharge current to dim a fluorescent lamp. An electrode heating circuit is connected to secondary windings of the transformer to continuously heat electrodes. An oscillation frequency of the inverter is controlled such that it increases as a dimming factor is high and decreases as the dimming factor is low. A capacitor is connected in series with a path of an electrode heating current in the electrode heating circuit so that the heating current is increased when the dimming factor is high and decreased when it is low by utilizing a frequency dependency of an impedance of the capacitor. As a result, an electrode temperature is kept at an optimum temperature in both start time and dimming time, and the start characteristic and a lifetime of the fluorescent lamp are significantly improved.