A backlight using multiple light-emitting diodes as a light source and illuminating a liquid crystal display panel from its back, the light-emitting diodes being formed of units, the units each being a minimum unit of m×n (where m and n are natural numbers), includes a driving part configured to drive the light-emitting diodes on a unit-by-unit basis; a block setting part configured to group two or more of the units into a block; and a luminance controlling part configured to control the luminance of the light-emitting diodes of the block independently on a block-by-block basis.