Abstract: A reed operating system for a loom of the type wherein the advance position of a reed is altered. The reed operating system is comprised of a generally V-shaped swingable link through which the movement of a crank is transmitted to a sley sword to make swinging motion of the reed. The swingable link is rotatably mounted on and swingable around a pivot shaft which is mechanically connected to a hydraulic cylinder. The hydraulic cylinder so operates as to shift the position of the pivot shaft in a predetermined distance in a predetermined direction in accordance with a predetermined pattern, thus altering the advance position of the reed while hardly altering the backdown position of the reed.