PURPOSE: To save great labor cost resulting from man-power by making it possible to rig a hall for a particular purpose and transferring constitution elements to actuation positions or turning them back to a housing position.

CONSTITUTION: This platform system is provided with at least two independent units of platforms 1, 2 and an upper floor 20 face. These platforms 1, 2 are constituted of a vertical support structure moving in accordance with a lifting means respectively. The support structure is provided with a storage space 4 openable to at least one side part and formed to house at least a technical constituting part 6 to rig the hall, and the storage space is interlocked to a transfer means formed to transfer the technical element 6 between a non- actuation position in the housing space 4 and an actuation position outside the housing space 4.