To provide a lighting system, capable of enhancing flexibility level of connection between a dimmer and a luminaire for dimming and of responding to the demand for opening of a market.

This lighting system has the dimmer 1 for generating dimming signals Sa-Se in a control part 6 according to an output level signal of an output level setting part 5 and for outputting the dimming signals Sa-Se from dimming signal output parts 7a-7e; a ballast 3 for dimming for outputting the dimming signals Sa-Se by converting them into a lamp signal; and a lamp 4 dimmed by the lamp signal. The system is structured so that a dimming signal type setting part 12 is installed in the dimmer 1, the control part 6 stores plural kinds of dimming signal types in advance, the dimming signal type is selected, based on the setting signal of the dimming signal type setting part 12, and the dimming signals Sa-Se of the selected dimming signal type are outputted.