A lighting device includes a light source that includes at least one LED element and a module including a substrate on which the light source is mounted, and a holder in which at least a part of the module is arranged and held. The holder includes a cylindrical portion that includes a stepped portion and a flange of a heat conductor extending from an outer peripheral edge of the stepped portion on which the substrate is arranged, and the holder includes an insulation layer that covers at least outer peripheral surface of the cylindrical portion.