To provide a water treatment plant control system capable of operating a highly reliable water treatment plant by appropriately and stably controlling the operation of a water treatment plant for performing the water treatment of water to be treated.

A water treatment plant control system 1 is provided with a water treatment plant 2, a low rank level control system 4 for controlling a plurality of water treatment devices 3 of the water treatment plant 2, and a high rank level control system 6 for controlling a plurality of low rank level controllers 5 of the low rank level control system 4. Each low rank level controller 5 controls the water treatment device 3 by the feedback control system of one input/one output. The high rank level control system 6 is provided with high rank level controllers 8, 10, and 11, and a data base 9 and an operating state noticing means 12 are connected to the high rank level control system 6. Also, a measuring device 7 is disposed between the water treatment plant 2 and the high rank level control system 6.