To obtain a bright comfortable room by sufficiently taking in light even in a room positioned on a north face, to which natural light is difficult to enter from a window.

An opening ceiling section 52 installed to a living room 32 is opened in the upper section of a closet 24 mounted on the third living room 12 facing the north side of a first floor. An open-close door 24a taking in and out clothes from the third living room 12 side and a top board 24b are set up in the closet 24. Ground glass 54 partitioning the third living room 12 and the opening ceiling 52 is arranged between the upper section of the closet 24 and the ceiling 12a of the first floor. A lighting apparatus 56 downwards irradiating the opening ceiling section 52 with light is disposed to a spandrel wall 34 fitted along the stair 22 of a second floor.