The present invention provides a backlight module comprising a light emitting unit including a light source and a light guide plate transmitting light from the light source; a light guide unit accumulatively placed on the top of the light emitting unit and transmitting the light to the upper part of the light guide unit; a mold frame containing the light emitting unit and the light guide unit and having a space between the side of the light guide unit and the mold frame; and a shielding portion formed at the side of the light guide unit to prevent light leakage transmitting from the side of the light guide unit to the outside of the light guide unit.