To easily compare data at the time of changing brands by showing data that is operated with the combination of designated brand numbers by a history request at the time of changing names of paper pulp.

A data collecting and processing part 11 takes in process data in a transient state after a brand is changed based on data collection cycle and period and the specification of group allocation of data to be collected, processes it in a brand unit and also with a brand associated with a date and allocates it to designated groups 1 to n. Process data in a transient state after brand change is stored in a process data storage device 16 through an output terminal of a brand name which currently operates in brand number switching parts 14-1 to 14-n. When an inputting means designates the combination of brand names, a group number and the date and time to a display data selecting part 17, the data that corresponds to designated brand names is selected and fetched from the process data storing part 16 and is shown on a CRT monitor 18.