In a process control system according to the present invention, a history record table, a history record relationship table, a process table, and a process relationship table are provided. The history record table stores information on a history record. The history record relationship table stores information on a history record relationship. The process table stores information on a process. The process relationship table stores information on a process relationship. When a history record is received, history records of the previous process and the next process are searched. Then, both of the history record relationship between a history record of the present process and a history record of the previous process and the history record relationship between the history record of the present process and a history record of the next process are created. Then, using the process table, the process relationship table, and history record information that has been already collected, history records that have not been received are estimated and then are displayed according to work order.With such arrangement, it is possible to trace a product item correctly even when some of history records are not registered since time required to register a history is varied depending on the processes or for other reasons, or there are not some of necessary history records.