A light guiding body that guides light includes, a light guiding portion, and an introducing portion including a plane of incidence and a curvature surface connected to the plane of incidence to guide the light to the light guiding portion by being connected to the light guiding portion, wherein an angle θ1 formed by a line segment connecting a first point on the plane of incidence and a second point on the curvature surface and a normal of the curvature surface at the second point satisfies θ1≧sin−1(1/n), where n is an index of refraction of the light guiding body.