A lighting system includes: a plurality of lighting devices; a controller; and a sensor which detects brightness of a region illuminated by at least two lighting devices among the plurality of lighting devices, wherein the controller includes a lighting controller operable in a plurality of operation modes, the plurality of operation modes include a sensor mode, and when the lighting controller obtains an instruction to operate in the sensor mode, the lighting controller performs (a) transition control for controlling the at least two lighting devices, by transmitting a transition instruction, to cause the at least two lighting devices to provide illumination at a predetermined dimming level, without using a result of detection by the sensor, and (b) dimming control for controlling the at least two lighting devices to cause the brightness indicated by the result of detection by the sensor to approach the target value, after transmitting the transition instruction.