Light guide and image scanning device

A light guide includes an incident surface provided at an end portion of the light guide in the longitudinal direction and upon which light emitted by a light source incidents; an emission surface being flat-shaped, the emission surface emitting the light that enters the light guide through the incident surface to an illumination target; a reflective surface having a parabolic shape to generate collimated light directed toward the emission surface by reflecting light from a focal point of the parabolic shape or light from a predetermined area including the focal point, and a light scatterer having a predetermined scattering area to scatter light that entered the light guide through the incident surface and reflect light that entered the light guide through the incident surface in a direction of the reflective surface. The emission surface includes a first emission surface that has a predetermined length from an end portion of the light guide facing the light source along the longitudinal direction, the emission surface being set to an angle at which, among the light scattered by the light scatterer, the collimated light generated by the reflective surface is totally reflected.