The present invention is a side-surface light-emitting unit to illuminate one or more illuminated objects disposed on a flat surface to extend in one direction, from a side surface of the illuminated object and includes a light guiding body which is disposed along the side surface of the illuminated object and emits light toward the side surface of the illuminated object, and an LED disposed at at least one end of light guiding body, an upper surface and a lower surface of the light guiding body except the side surface facing the object being optically shielded. It is possible to brightly illuminate objects such as key switches or the like from one end of the arrangement along a direction of the arrangement by uninterrupted continuous emission light.