PROBLEM TO BE SOLVED: To provide a tension controlling mechanism effective for preventing the relaxation of a membrane such as a thermoplastic resin film generated after stretching the membrane and defects caused by the relaxation, especially a mechanism having excellent tension controlling performance of a fluororesin film having a characteristic problem in the stretching of the film and provide a membrane building provided with the tension controlling mechanism. SOLUTION: The tension controlling mechanism for a membrane controls the tension of the membrane of a building having a membrane roof. It has a bolt-holding member having a bolt-hole and fixed to the building, a bolt having a male screw part, rotatably fixed to the bolt-hole of the bolt-holding member and rotatable without moving relative to the bolt-holding member, a female screw part engaged with the male screw part of the bolt, and a membrane holding member having a membrane holding part to hold the membrane and moving in the longitudinal direction of the bolt without rotation by the rotation of the bolt. The building is provided with the tension controlling mechanism. COPYRIGHT: (C)2005,JPO&NCIPI
