A device for controlling the tension of the knitted fabric includes two parallel rows of rollers, which are supported by two plane surfaces mounting two needle beds upon which a carriage is able to move longitudinally and alternately.The rows of rollers are located beneath the needle beds with the rollers of the first row, able to turn in a single direction, being in contact with the corresponding rollers of the second row, thus creating a series of independent pairs of rollers between which the knitted fabric is inserted.Each pair of rollers is moved by a rod, mounted on the second plane surface, featuring a heel upon which moving cams act determining the consequent rotation of the corresponding pair of rollers, while fixed cams, acting upon the heels, return the rods to their initial position.