A plurality of lighting devices are respectively arranged, on a ceiling surface, at a plurality of grid points of the ceiling surface partitioned in a grid pattern. A detection unit detects occupancy statuses of a plurality of seats located correspondingly to positions of the plurality of grid points. A controller is capable of communicating with each of the plurality of lighting devices. The controller includes a light-control information generating unit that regards a block formed of a plurality of grid points centering around a grid point of an occupied location as one group to generate, for each of groups set correspondingly to occupied locations, light control information on a lighting device that becomes a dimming target in the group. The controller also includes a transmission unit that transmits the light control information. The lighting device being a dimming target among the plurality of lighting devices performs light control based on the received light control information.