A discharge lamp ballast apparatus includes a DC/DC converter having a
transformer T1 and a DC/DC converter having a transformer T2, which are
connected in parallel; a control section 4 for controlling the output
voltages of the DC/DC converters by varying their duties with shifting
the operation phases of the transformers T1 and T2 of the DC/DC
converters; and a voltage-multiplier rectifier circuit having diodes 7-9
and capacitors 10-12 for generating a high voltage used for starting a
discharge lamp 22 by utilizing the potential difference between the
output voltages of the transformers T1 and T2.