An illumination unit includes a light guide to guide primary light, a conversion member to convert the primary light into secondary light, and a holder holding an exit end of the light guide and the conversion member. The holder includes an entrance portion that the primary light enters, an exit portion to emit illumination light including the secondary light, and a fixing portion fixing the conversion member between the entrance portion and the exit portion in a direction of a central axis of the primary light. The fixing portion is arranged in a planar region perpendicular to the central axis of the primary light and on an inner peripheral face of the holder. The conversion member is in contact with the fixing portion.
