A blood purification system is provided that is capable of effectively utilizing accumulated histories stored during blood purification treatment and that helps take a quick and appropriate action in response to a particular incident that occurs unsteadily. In a blood purification system, a history stored in a storage device includes particular incidents having occurred unsteadily in blood purification treatment. The blood purification system includes an extracting device capable of searching the histories accumulated in the storage device and extracting a desired one of the particular incidents, a calculating device capable of calculating a time when the particular incident extracted by the extracting device occurs a predetermined or more number of times as a frequent-occurrence time slot, and a display control device capable of displaying the frequent-occurrence time slot calculated by the calculating device on a display during a current session of blood purification treatment.