We conducted an experiment that incorporated as factors a warning signal before a change of lighting and various lighting positions.Regarding warning before a change of lighting, it was found that the perception rate and degree of concern about the brightness change were low for the lighting of the seat on the separate work island, and magnitude of the change in the subject's visual field affects the perception.It has been found that the degree of concern of a worker about a change in brightness of fluctuating lighting is correlated with the amount of change of illuminance.