PURPOSE: To measure the shape of a roll in the inline state quickly with a high precision, by allowing a mimic rolling material, where plural contact distance sensors are buried in an elastic material, to pass between rolls to be measured.

CONSTITUTION: In respect to a base material 11 of a mimic rolling material 1 having the roll width of a rolling mill, many contact distance sensors 14 are buried in an elastic material 13 consisting of a hard rubber. Sensors 14 detect the extent of movement of a plunger by the output of a differential transformer and is provided with an electronic circuit device 2 for transmission to the external. In case of measurement, the rolling material 1 is allowed to pass between rolls, and sensors 14 are subjected to rolling reduction in accordance with shapes of rolls, and the output of every sensor 14 is outputted to an external operation processing device through the device 2. In the processing device, outputs of sensors are scanned and are converted to a numeric value indicating the radius of the roll and is displayed and recorded as prescribed. Thus, the shape of the roll is measured in the inline state quickly with a high precision, and the rolling material 1 is used repetitively.