An illumination device includes a light emitting unit, a light guide member, in which one end part in a longitudinal direction has a rod shape facing the light emitting unit, and is formed on a peripheral surface thereof with a light emitting part extending in the longitudinal direction, and a support member that extends along the longitudinal direction of the light guide member and supports the light guide member, wherein the support member is divided into a one side divided part and the other side divided part in the longitudinal direction of the light guide member, and a gap is provided between a support surface of the light guide member in the one side divided part and a support surface of the light guide member in the other side divided part.