To make a solid structure by work only to contract each of side frames from a flat developed shape on a ground surface part and to develop it on the ground surface part by extending each of the side frames in the opposite way.

Each of beam frames 10 to constitute a roof bottom surface to be an (n) angular shape (n≥3) is constituted free to extend and contract, it is constituted of a plural number of roof frames 14 both sides of which are hinged at an intersection point position of each of the beam frames 10 and intermediate parts of which are free to fold through a hinge, the respectively hinged roof frames 14 constitute a truss in a state of contracting each of the beam frames 10, they are concentrated at one point with an intermediate hinge 16 as its ridge part top point, and the roof frames 14 are devised to be developed on a flat surface along the beam frames 10 in a state of extending each of the beam frames 10.