Abstract: Apparatus wherein a plurality of rings disposed in the direction of the width of a strip are pressed against the surface of the strip being rolled, and the distribution in the direction of the width, of the components of the tension of the strip as act on the respective rings is detected, thereby to detect the shape of the strip, characterized in that a plurality of cylindrical springs are fitted in the interspace between the inner periphery of each ring and the outer periphery of a shaft which rotates along with the rings, and that a gap sensor which detects the amount of eccentricity of the corresponding ring attributed to the component of the tension of the strip is arranged in the vicinity of the outer periphery of each ring.