PURPOSE: To interconnect terminals on many manufacturing lines and to manage the progress of manufacture at a low cost by a method wherein telephone sets inputting the minimum number of parts and lot numbers are mounted to both ends of each manufacturing line, and data from the telephone set is transmitted to a computer through an exchanger.

CONSTITUTION: Telephone sets are mounted to both ends of each of a plurality of manufacturing lines, and on exchanger 4 is connected to a computer 1 through a communicating circuit 3. The manufacturing ling forms, for example, an assembly line for a television set, and in addition to a work station 2 with a printer, a master file and a transaction file are connected to the computer 1. A telephone set to which a counter key #1 is mounted is generally turned OFF with a hook key pressed and turned ON with the hook key released from press, and a counter key #1 which is formed such that relation described above is reversed and by which a counter is worked each time a key is pressed is provided. This constitution facilitates counting of the number of parts on the manufacturing line. Further, a lot number can be inputted by means of a ten- key.