The present invention provides a backlight of a liquid crystal display device having an inclination surface on a light guide plate and preventing a breakage of a liquid crystal panel, wherein light which leaks from the inclination surface is made to return to the light guide plate and the adhesiveness of the light guide plate and a flexible printed circuit board is increased. In a liquid crystal display device having a backlight which radiates light to a liquid crystal panel, LEDs are formed on a light guide plate formed on the backlight as light emitting elements. Between the plurality of light emitting elements, a projecting portion of the light guide plate is formed, and a reflection member is formed on an adhesive sheet which adheres a projection member and a flexible printed circuit board to each other. By arranging the reflective member and the cushion member close to an inclination surface, light from the inclination surface is made to return to a light guide plate side, and an external force from the outside can be alleviated by a cushion member.