A backlight module includes at least one light emitting device capable of emitting a light beam, a light guide plate, and a thermal insulation light guide element. The light guide plate has two surfaces opposite to each other and a side surface connecting the two surfaces. The light emitting device is disposed beside the side surface. The light beam enters the light guide plate through the side surface. The thermal insulation light guide element has a light incident surface and a light emitting surface. The light incident surface having at least one first recess is located in a transmission path of the light beam and between the light emitting device and the side surface. The light emitting surface is disposed between the light incident surface and the side surface. The glass transition temperature of the thermal insulation light guide element is higher than that of the light guide plate.