A through anchor suitable for use in a seat belt system is disclosed. In use, the through anchor is mounted by way of a through bore formed in a fixing member arranged on a side of a vehicle body. The through anchor comprises a metal plate, a fixing bolt, a resin covering and an internally-threaded member. The metal plate defines therein a through hole and a webbing slot. The fixing bolt has a head portion, a threaded portion and a base portion. The resin covering is molded as an integral member on a surface of the head portion of the fixing bolt and a surface of the metal plate. The internally-threaded member has a cylindrical portion and a flange portion extending radially and outwardly from the cylindrical portion. In use, the internally-threaded member is threadedly mounted on the fixing bolt with the fixing member interposed therebetween, the cylindrical portion extends through the through bore and encloses therein the threaded portion of the fixing bolt, and the flange portion holds in place the fixing bolt relative to the direction of an axis of said fixing bolt.