A business information management system includes a data connection relationship information storage section storing connection relationships of data items forming a business information database, a data connection accuracy information storage section that stores data connection accuracy between data item pairs having a connection relationship, and a data change section that changes data in the business information database by inputting data thereto. A change affected data extraction section extracts change affected data items by tracing first data items having a connection relationship with an originally changed data item and second data items having a connection relationship with the first data items until there is no connection relationship, a change effect probability calculation section calculates change effect probability of the change affected data based on data connection accuracy, and a change affected data display section displays the change effect probability on a display unit.