According to one embodiment, a lighting device includes a hollow main body having thermal conductivity, a light source having at least a semiconductor light-emitting element, an accessory element, and an adiabatic member. The light source is thermally coupled to the main body. The accessory element has an allowable temperature limit different from that of the light source, and is accommodated in the main body. The adiabatic member divides the main body into a first region thermally coupled to the light source, and at least a second region thermally coupled to the accessory element and thermally isolated from the first region.