To provide a lighting system in which occurrence of a failure in a circuit board or a circuit component due to an incorrect installation of a board cover can be suppressed.

The lighting system is provided with a cold-cathode tube 17, a chassis 14 in which the cold-cathode tube 17 is housed, a control board 40 which is installed in the chassis 14, a board cover 60 which is installed on the chassis 14 and arranged so as to cover the control board 40. A plurality of projecting parts 52 which protrude toward the board cover 60 are provided at the installation parts of the board cover 60 in the chassis 14, and cover-side through holes 63 into which the projecting parts 52 are inserted are formed in the board cover 60. One of projecting part 52 out of the projecting parts 52 has a larger cross-sectional maximum dimension crossing the projection direction of the projecting part 52 than a hole diameter of the cover-side through hole 63 into which the other projecting part 52 is inserted.