An electric power demand control system selects a presswork device as a target of electric power demand control in a case where the ratio of the total time length of a non-working state of the presswork device within a time period to the total time length of a working state of the presswork device within the time period is larger than a threshold. This makes it possible to alleviate, for example, (i) a decrease in production efficiency caused by electric power demand control at a facility at which production lines are installed and (ii) environmental deterioration due to electric power demand control.