Provided is an excimer lamp light source device that achieves low cost and avoids the occurrence of narrowly-defined contracted discharge by adopting a lamp bulb having a simple structure and of the type in which a discharge current is passed in a tube axis direction.
The excimer lamp light source device includes: an excimer lamp that has a pair of external electrodes configured to induce an electric discharge in a discharge space of a lamp bulb and to cause a discharge current to flow in a tube axis direction of the lamp bulb, and that generates UV light in the discharge space by the discharge, the lamp bulb enclosing the discharge space filled with a discharge gas configured to generate xenon excimer molecules, having a shape in which both ends of a tubular body are hermetically sealed, and having an easily dischargeable substance layer that can easily cause a discharge formed on at least a part of a surface that is in contact with the discharge space; and an inverter having a transformer equipped with a secondary winding to which the external electrodes are connected in order to apply a high-voltage alternating current to the excimer lamp. The inverter supplies power lower than power that causes a linear discharge.