To exactly grasp production progress situation on plural production lines in real time at one head office of production management and to enable control by applying required instructions to the production lines.

A plant is provided with plural production lines 1a, 1b... private radio exchange station 17 and plant base station 20, packet data from a line control part 10 for controlling the production lines 1a, 1b... are received by the private radio exchange station 17, these received packet data are sent through a LAN cable 18 to the plant base station 20, and the packet data are transmitted from this plant base station 20 to a production managing station 24 at a head office 22 of production management. The data transmission from the production lines 1a, 1b... to the head office 22 of production management is performed through one-sided communication due to a high-speed LAN system L2, and the instructions from the head office 22 of production management to the respective production lines 1, 1b... are performed by using a private telephone line 26.