An illumination apparatus includes a light source and a light guide formed in a rod shape. An end surface in a longitudinal direction is an incident surface that receives light emitted from the light source. Diffusing patterns are formed on the light guide, and intervals between the diffusing patterns closer to the incident surface in a first area close to the incident surface are smaller than intervals between the diffusing patterns closer to the incident surface in a second area farther from the incident surface than the first area.