a shape control system for a rolling mill comprises means for operating a roll positioning means to press down the rolls under a preselected load , when no strip to be rolled is fed between the rolls ; a calculator of roll position variation for comparing the roll position under the preselected load with a preselected reference roll position ; a calculator of roll crown variation for calculating the roll crown variation by using the output from said calculator of roll position variation and a preselected functional relationship ; and a calculator of roll bending force for calculating the amount of a roll bending force to be corrected based on the output from said calculator of roll crown variation and feeding the thus calculated correction to roll bender control means .