Optical element and light-emitting device

A light emitting device comprising a plate-like light guiding section for guiding light, and a light emitting component for emitting the light:

• in which
• the light guiding section includes, on a surface of one side thereof, a prism section the cross-sectional shape of which is composed of a plurality of saw teeth placed on polygonal shapes having one common center for changing traveling directions of the light guided by the light guiding section,
• the light emitting component is placed for the emitted light to enter the light guiding section at the common center,
• the protrusion angle of the saw teeth at positions away from the common center is larger than the protrusion angle of the saw teeth at positions near the common center so that the incident angle at which parallel light guided by the light guiding section enters reflective surfaces of the saw teeth at positions away from the common center is larger than the incident angle at which the parallel light guided by the light guiding section enters reflective surfaces of the saw teeth at the position near the common center, and
• the protrusion angle of the saw teeth is changed according to their positions in polygonal shapes.