A lateral light emitting device is formed by fusing one end of a rod lens to an end surface of an optical fiber, and by fusing a prism to another end of the rod lens. The prism has a basic shape including a planar light emitting surface parallel to an axis formed by cutting part of a circumference of a cylinder and has a distal end inclined surface, a distal end portion of which is diagonally cut. Alternatively, a prism lens is fused to the end surface of the optical fiber. The prism lens has the same basic shape described above.