A backlight module includes a light guiding plate, a frame element, a light bar and a light-bar cover. The light guiding plate has a light output surface. The frame element includes a bottom surface and a side wall, the bottom surface is parallel to the light output surface of the light guiding plate, and the side wall is extended from the bottom surface and towards a direction perpendicular to the light output surface. The light guiding plate is disposed in the frame element. The light bar is disposed in the frame element and between the side wall and the light guiding plate. The light-bar cover is disposed on the light bar and includes a covering portion substantially parallel to the bottom surface of the frame element. The light bar and the light guiding plate are disposed between the covering portion and the bottom surface of the frame element.