PURPOSE: To provide the back light for liquid crystal display capable of locating a light source in a place exclusive of the rear surface of a liquid crystal display plate, saving space and suppressing a decrease in luminance as far as possible.

CONSTITUTION: This back light has a reflection plate 2 located on the rear surface of the liquid crystal display plate 1 and the light source for irradiating the reflection plate with light L from between the liquid crystal display plate and the reflection plate. The reflection plate 2 has many pieces of ruggedness 22 having light transmissivity on its surface. The liquid crystal display plate 1 is irradiated with the light curved by transmitting the inside of the ruggedness 22 from the rear surface.