The purpose of this study is to reveal what determines the perception of lighting fluctuation. We focused on two factors; the illuminance ratio and the change rate. We conducted two experiments about the perception of lighting fluctuation in the room that was assumed an office. The subjects were asked to perform a hand calculation or typing activity, during which they should acknowledge whether they have perceived the change of illuminance. As a result, it was revealed that the effect of the change rate differs depending on the illuminance ratio.
