To provide a method for increasing construction efficiency when installing a lighting structure inside a roof or under the roof.

Light of a porch illuminating lamp 6 is introduced by providing a first lighting part 2 on the roof 1 over an entrance, placing a first introducing tube 3 immediately below the first lighting part 2 for connecting a window 4 of an entrance-ceiling, placing the porch-illuminating lamp 6 on a porch-ceiling under the roof 1 over the entrance, installing a second introducing tube 7 letting in the porch-illuminating lamp 6 to be housed inside the roof 1, and bringing the second introducing tube 7 with the first introducing tube 3 and the porch-illuminating lamp 6 closer to the window 4.