A lamp operation device includes a mode setting part that sets an operation mode for lamps, and a lamp operation part that controls switching between the lamps in accordance with the set operation mode. The lamp operation part includes a process corresponding to a manual switching mode in which a lamp selected by a user is set as an illumination lamp, and a process corresponding to an automatic switching mode in which the plurality of lamps is automatically set in sequence as an illumination lamp. In the automatic switching mode, after one lamp has been set as the illumination lamp, cumulative illuminating time (amount of change) of the lamp is measured. Then, the illumination lamp is switched to the other lamp, depending on whether a measurement result has exceeded predetermined threshold time.