A high-voltage generating transformer for a discharge lamp lighting apparatus according to the present invention includes a rodlike core; a secondary winding bobbin that is divided into a plurality of sections, and where the core is disposed in the central portion thereof; a secondary winding part wound on the secondary winding bobbin, divided between the plurality of sections of the bobbin; a primary winding bobbin disposed around the outer periphery of the secondary winding part; and a primary winding part wound on the primary winding bobbin; wherein the primary winding bobbin is changed in thickness every section or every plurality of sections of the second winding part such that the bobbin has a thickened thickness on the side where the potential difference between the primary winding part and the secondary winding part is high, and the bobbin has a thinned thickness on the side where the potential difference is low.