A discharge lamp driving device according to one aspect of the invention includes a discharge lamp driving section configured to supply a driving current to a discharge lamp including electrodes and a control section configured to control the discharge lamp driving section. The control section controls the discharge lamp driving section such that a mixed period is provided in which a first period in which an alternating current having a first frequency is supplied to the discharge lamp and a second period in which a direct current is supplied to the discharge lamp are alternately repeated. The first frequency includes a plurality of frequencies different from one another. The control section temporally changes the length of the first period.