The disclosure improves the quality of seams in sewing using a sewing machine, and includes: a holder (11) holding fabric (S); a driver (12) being detachable from a bed (7) of a sewing machine (1) and driving the holder along an upper surface (7a) of the bed; a position detector (13) detecting a position of a sewing needle (3) of the sewing machine in an up-down direction; and a controller (16) controlling driving of the holder, which is performed by the driver, based on a detection result of the position detector.