To solve problems that the number of LEDs of a both-face light emission type backlight increases and that power consumption increases, and provide a display device of a low power consumption and a surface light-emitting device, in a liquid crystal display device such as a both-face panel.

An air layer of the LED of the backlight and a light guide plate are excluded by an optical adhesion layer. The optical adhesion layer is to be of approximately the same refractive index as that of the light guide plate. By this, utilization efficiency of light of the LED increases, and reduction of the number of LED chips becomes possible. Because of this, the display device and the surface light-emitting device which are low in power consumption and inexpensive can be provided.