A discharge lamp drive apparatus includes: an inverter circuit; a
transformer; a plurality of discharge lamp connection terminals; a
plurality of ballast capacitors; a plurality of voltage detection
circuits; and a signal processor. Each voltage detection circuit has
first and second voltage detection elements constituting a series
circuit. Each series circuit has a first end connected with a
corresponding one of the discharge lamp connection terminals and a second
end connected with a grounding terminal. The signal processor generates a
signal indicating an open state of a discharge lamp by using an average
value and a peak value of voltages appearing between connection points of
the first and second voltage detection elements and the grounding
terminals.