To provide a device capable of surely preventing light-dimming state setting contrary to intention of an illumination installer, as compared with a system of switching light dimming states with an ON/OFF operation of a power source switch.

A discharge lamp lighting device 100 is provided with a lamp detection circuit 90, and a microcomputer 80 equipped with a nonvolatile memory 81. The lamp detection circuit 90 detects mounting/non-mounting of a discharge lamp. The nonvolatile memory 81 stores correspondent information making the number of times of attachment and detachment of the discharge lamp 42 corresponding to an output mode of the discharge lamp 42. The microcomputer 80 determines if the discharge lamp 42 is attached and detached by any of the numbers of times shown by the correspondent information stored in the nonvolatile memory 81 based on detection results of the lamp detection circuit 90, and if it determines that the lamp is attached and detached at either number of times, it lights the discharge lamp 42 at an output mode correspondent to the number of times concerning the determination out of the correspondent information.