To provide a lighting device capable of accomplishing optimum luminous efficiency without redesigning its DC power supply even when a dielectric barrier discharge lamp of a different specification is mounted on the lighting device.

A dielectric barrier discharge lamp 14 is composed of a long tubular airtight container 141 capable of transmitting ultraviolet ray, an internal electrode 142 disposed in the airtight container 141 along its axis, a semi-cylindrical external electrode 143 in close contact with the outer surface of the airtight container 141, and excimer-forming gas filled in the airtight container 141. A converter 12 is input an AC voltage from a power supply 11, converts it into a DC voltage, and outputs the DC voltage. An inverter 13 generates a high-frequency wave using a DC voltage supplied from the converter 12 to cause the dielectric barrier discharge lamp 14 to induce dielectric barrier discharge and emit ultraviolet ray. The converter 12 is so constructed that the outputs of DC power supplies 121 and 122 are connected in series. By changing the number of the DC power supplies, it is possible to accomplish optimum luminous efficiency for any dielectric barrier discharge lamp of different specifications.