A flat panel display lighting system 20 includes: semiconductor light-emitting device 10; board 21; and light guide plate 22. The device 10 includes an inverted T-shaped substrate 1 having a base portion 1a, on which a pair of electrodes 2 and 3 are formed, and a mounting portion 1b, on which a light emitter 4 is mounted. The device 10 is mounted through the board 21 with the mounting portion 1b set through an opening 21a formed in the board 21. A light guide plate 22 is mounted on the board 21 so that a face of the plate 22 faces the light emitter 4. Each of the pair of electrodes 2 and 3 is formed on the substrate 1 of the device 10 so as to be electrically connected to the light emitter 4 and to a circuit pattern formed on the board 21.