Abstract: Length of an elongated belt-like cloth receivable in a treatment tank is increased by a compact and simple mechanism, and, moreover, impact force applied to the cloth is enhanced, whereby efficiency in cloth treatment such as washing in water, scouring, dyeing and treatment quality are improved. A treatment tank 10 used in carrying out the invention is divided into a front chamber 12 and a rear chamber 14, and a cylindrical rotary member 28 comprising a plurality of rods 30 arranged to form a cylinder is disposed on the midway of a passage 26 communicating the two chambers. A predetermined length of the cloth 20 is fed into the treatment tank, and the cylindrical rotary member is rotated alternately in forward and reverse directions, whereby conveyance of the cloth is repeated between the front and rear chambers, and during such repetition of conveyance, a required treatment is applied to the cloth.