A backlight unit (49) for a display device (69) provided with a liquid crystal display panel (59) comprises a chassis (41), a diffusion plate (43) supported by the chassis, and point-like light sources supported by mounting substrates (21) provided on the chassis. The point-like light sources comprise LEDs (22) mounted on the mounting substrates. The mounting substrates are connected to each other by connectors (25) to form rows (26) of the mounting substrates, and the rows (26) are arranged side by side. The rows of the mounting substrates each consist of two, short and long mounting substrates, and the rows are arranged in a mixed state in such a manner that each row consisting of the two, short and long mounting substrates is reversed with respect to each other. As a result, the positions of the connectors are not aligned rectilinearly in the direction in which the rows of the mounting substrate are arranged.