A pile warp tension controller for controlling the pile warp yarn tension control mechanism of a pile fabric loom controls the position of the tension roller of the pile warp yarn tension control mechanism or the torque acting on a tension lever supporting the tension roller according to the operating state of the pile fabric loom so that the tension of the pile warp yarns is regulated at an optimum value. The control mode of the pile warp tension controller is changed over from a tension control mode to a speed control mode in forming loops of the pile warp yarns to ensure the satisfactory formation of loops having a predetermined loop length and to prevent defective loops.