The present invention relates to a backlight apparatus and a liquid crystal display apparatus, capable of realizing a backlight apparatus having high color reproductivity without color irregularities in a backlight apparatus having a LED device as its light source. In the optical unit 61, there are disposed the dichroic mirror B which transmits green light Lg and red light Lr and reflects blue light Lb, the dichroic mirror G which transmits the light Lb and the light Lr and reflects the light Lg, and the dichroic mirror R which transmits the light Lb and the light Lg and reflects the light Lr, and they transmit or reflect the light emitted from the LED devices 11B, 11G and 11R to mix to form the white light Lw. The light Lw formed by the dichroic mirrors B, G and R is entered to the light guiding plate 62 by the mirror performing a total reflection. Therefore, in the backlight apparatus having an LED device as its light source, it is possible to realize a backlight apparatus having high color reproductivity, without color irregularities.