A light source apparatus capable of reliably enhancing the starting performance of a high pressure discharge lamp even during hot state just after extinguishing the high pressure discharge lamp by radiating a necessary and sufficient amount of a UV-light into a discharge bulb of the lamp using an UV-enhancer of a simple constitution without increasing the manufacturing cost is provided. An UV-enhancer 3 for radiating a UV-light to a discharge bulb for enhancing the starting performance of a high pressure discharge lamp 1 upon starting lighting includes a discharge tube 18 connected in parallel to a lighting circuit 11 of the lamp 1, and an external electrode 20 of the discharge tube 18 is formed as a metal holder H1 that holds the outer periphery of the discharge tube 18 so as to oppose the end face of an electrode seal portion 9L of the lamp 1 inserted through a bottom hole 14 in a concave reflector 2 and secures the electrode seal portion to an electrode lead 8 protruding from the end face thereof.
