To provide an opening/closing body device capable of securing the visibility of a display member containing a luminous material in a closing state while suppressing the consumption of energy.

An opening/closing body device 1-1 comprises: an opening/closing body 2 configured to open or close an opening part 101 formed in a structure 100 communicating a first space S1 with a second space S2; a storage part 3 formed on a wall face 104a forming the first space S1 for storing the opening/closing body 2 in the opening state that the opening/closing body 2 opens the opening part 101; and a luminous display member 4 which is provided in the opening/closing body 2 and emits the rays of light by accumulating the rays of light. The luminous display member 4 is configured such that the luminous display member 4 is exposed to the first space S1 in the opening state, and that when the opening/closing body 2 is shifted from the opening state to a closing state that the opening part 101 is closed, the luminous display member 4 is deformed toward a first face 22 side as the face of the opening/closing body 2 forming the first space S1 in the closing state, and that at least a part of the section exposed to the first space S1 in the opening state is exposed to the first space S1 in the closing state.