To provide a display device in which misalignment of a diffusion lens can be suppressed and a work time for mounting the diffusion lens can be reduced.

A liquid crystal television device 100 includes a display unit 1, an LED 61 that irradiates the display unit 1 with light, a board 62 mounting the LED 61, a heat sink 63 that supports the board 62, and a diffusion lens 64 that is disposed to cover the LED 61 and diffuses the light from the LED 61. The diffusion lens 64 integrally includes an engaging part 64a for mounting the diffusion lent 64 on the heat sink 63, and a positioning part 64b separated from the engaging part 64a, for positioning the diffusion lens 64. The heat sink 63 and the board 62 have an engaging hole 63d and a positioning hole 62c, respectively corresponding to the engaging part 64a and the positioning part 64b of the diffusion lens 64.