A turbine support structure supports a turbine casing and is configured to be movable when the turbine casing is thermally deformed while a gas turbine is operated, thus preventing a fatigue fracture of the turbine casing from occurring. The turbine support structure includes a pair of supports, each having an upper and lower end, for supporting respective opposite side surfaces of the turbine casing at the upper end of either support; and a movable unit installed at the lower end of each support and configured to movably support the lower end of the support. The movable unit is spaced outwardly from the corresponding opposite side surface of the turbine casing, so that the corresponding support inclines toward the turbine casing and is rotatable. The lower end of each support is rotatably coupled to the corresponding movable unit so that the support is rotatable toward an axis of the turbine casing.