A method and an apparatus of removing works from each of the facilities in a production line is described in order to facilitate changing of a work monitoring operation in accordance with, for example, a layout change in the production line and a change in the facilities. Work tracking conditions are stored in a memory in the form of a table, and work tracking management data and plant status data which have been stored in the memory separately are retrived while the work tracking conditions are referred to, thereby extracting management data for which tracking conditions have been completed. The extracted management data is subjected to processing such as movement and updating in accordance with the contents of the above-described data which are referred to. In addition, in order to efficiently effect a process monitoring operation for each lot even when the arrangement of a lot consisting of a plurality of works joined together arbitrarily changes, such as, as a result of dividing the lot into a plurality of sub-lots, the arrangement of each lot is stored in the form of data of a tree structure, whereby the lot arrangement is readily changed by changing the tree structure.