A lighting system includes a lighting fixture, a demand controller and a control board. The demand controller obtains power usage of a plurality of devices including the lighting fixture and, outputs a demand signal depending on the power usage obtained. The control board includes a switch provided on a power line and a switch controller that interrupts supply of power over the power line for a predetermined period of time by controlling the switch based on the output demand signal. The lighting fixture includes a light emitter, a detector, and a controller that causes the light emitter to emit light in a second dimming state darker than a first dimming state in which the light emitter emitted light immediately before the detection, if the detector detects that the supply of power has been interrupted for the predetermined period of time.