A lighting apparatus includes a lighting tube 10 , a socket 20 and an adapter casing 30 . The lighting tube 10 has a lighting tube main body 11 , a seating portion 12 provided at a basal end portion of the lighting tube main body, electrode terminals 14 provided at the seating portion, and a connecting portion cover 40 covering a connecting portion formed between the lighting tube main body and the seating portion in a hermetically sealed manner. The adaptor casing 30 and the connecting portion cover 40 are detachably connected in a state in which the socket 20 into which the seating portion 12 of the lighting tube 10 is inserted is accommodated in the socket accommodation space 31 , whereby the socket 20 and the seating portion 12 of the lighting tube 10 are hermetically sealed by the adaptor casing 30 and the connecting portion cover 40.
