A light source drive device includes a supply unit that supplies a high-frequency first drive signal and a second drive signal whose frequency is lower than a frequency of the first drive signal to a discharge lamp which has a pair of electrodes, and a control unit that controls the supply unit so that the second drive signal is supplied during a second period after the first drive signal is supplied during a first period and the second period is lengthened as a voltage between the pair of electrodes is increased. It is preferable that the second period be longer than two minutes.