ROLL STATE MONITOR DEVICE

A roll state monitor device includes: rolling force detector configured to detect rolling force of a monitored roll selected from an upper roll set and a lower roll set; force variation value extracting means configured to extract a rolling force variation value based on the rolling force for each rotation position of the monitored roll; and identification part configured to identify a roll eccentricity amount of the monitored roll by acquiring a plurality of accumulated values by accumulating separately for each rotation position of the monitored roll a value which is one of the rolling force variation value and a roll gap equivalent value calculated based on the rolling force variation value, and by dividing each of the plurality of accumulated values by a correction coefficient corresponding to a roll rotation amount.