A vehicle light guide 40 that guides light from a light source 10 toward a projection lens 30 includes an incident surface 41 on which light from the light source 10 is incident, a reflective surface 45 that reflects light from the incident surface 41, and an exit surface 44 that outputs light reflected on the reflective surface 45. The reflective surface 45 includes, on at least a part thereof, a light diffusing part 50 where at least either one of a plurality of convex parts 51 and a plurality of concave parts 52 that diffuse light are formed.