A female screw set (11) includes a screw body (12) including a fixing threaded portion (121); and a nut (13). The nut (13) is screw fitted to a male threaded portion (122) formed on an outer peripheral surface of the screw body (12). A flange (123) is formed on the screw body (12). The flange (123) has a shape corresponding to a dedicated tool. At least one of the male threaded portion (122) or a female threaded portion (131) of the nut (13) includes a sliding structure (14) such that a screw fitting force of the male threaded portion (122) and the female threaded portion (131) is weaker than a screw fitting force in the fixing threaded portion (121).
