To provide an open-ceiling structure which enables a free change in the amount of ventilation of air, and sound-insulating and light-tightening performance by enabling upper and lower floors to be opened/closed by means of a screen member.

A pair of rail sections 14 and 14 is provided along boundary peripheral edges of opposed side wall in such a manner as to constitute a boundary peripheral edge between an open ceiling 10 and a space of a living room 11a. A light tightening section S movable along the pair of rail sections 14 and 14 is laid between the pair of rail sections 14 and 14. The light tightening section S, which is composed of a plurality of screen members 15, is provided slidably along the pair of rail sections 14 and 14 and rotatably in a sliding direction. In nonuse, all the screen members 15 are housed in an overlapped state on the one-end sides of the rail sections 14 and 14, respectively. In use, all the screen members 15 are arranged at regular intervals along the pair of rail sections 14 and 14, and rotated in a regular-interval state in conjugation with one another while being kept in a parallel state, so that the amount of gap between the respective screen members 15 can be freely varied.