To provide an isolated ceiling structure in which a camber is formed easily.

A horizontal member 16 is stretched between a girth 12 and a girder 13 in parallel with floor beams 14. The horizontal member 16 has an upward curved shape, and both end sections of the member 16 are placed on the top faces of lower-side flange sections in the girth 12 and the girder 13, and fixed onto the flange sections by bolts or the like. A hanger 18 has a height adjusting mechanism, a ceiling central section surrounded by walls is heightened smoothly when a space between the member 16 and a ceiling board 17 at the central section is narrowed gradually by the height adjusting mechanism and the camber is formed.