The present invention relates to an illuminating device and a method of assembling the illuminating device, wherein the illuminating device comprises a tubular casing, an electrical connector connected with the casing, a drive unit at least partially received in the electrical connector, and a light-emitting unit received in the casing, wherein the light-emitting unit comprises a carrier, wherein the electronic parts of the drive unit and the light-emitting parts of the light-emitting unit are arranged on the carrier.