In a backlight device according to the present invention including a light emitting diode substrate, which has a light emitting diode and is placed on the back side of a panel module having an image display surface on the front side, and a reflection sheet for reflecting light emitted by the light emitting diode to the panel module, the reflection sheet is placed on the front side of the light emitting diode substrate, and the reflection sheet is provided with a through-hole into which the light emitting diode is inserted, so as to reduce brightness unevenness and color unevenness on the image display surface resulting from the light emitting diode substrate.