To provide a backlight device with a positioned light guide member and with a wiring member mounting a light-emitting element free from fear of injury.

The light-emitting element 12 emits illuminating light. The wiring member 18 mounts the light-emitting element 12. The light guide member 13 is equipped with a side end face 13a for the illuminating light to be incident into and an emission face 13d emitting the illuminating light. A case body 14 holds the light-emitting element 12, the wiring member 18 and the light guide member 13. The case body 14 is made of a metallic material, and has a bottom wall part 14a and side wall parts 14b. A protrusion part 14c positioning the light guide member 13 is formed in the case body 14. A contact part 13e abutting to the protrusion part 14c is formed on the light guide member 13. The protrusion part 14c is formed on the side wall part 14b of the case body 14.