To carry out continuous treatment of processing machines independently of cleaning of wastewater treatment facilities and to make introduction of a new processing process easy by utilizing already existing facilities.

The wastewater treatment system is for treating wastewater discharged out of a plurality of processing machines 10 and a center container 14 for storing wastewater 16 discharged out of the processing machines 10 is joined to a plurality of wastewater treatment units 30 each comprising an intermediate container 40 with a smaller capacity than that of the center container 14, a circulation route 42 to turn back to the intermediate container 40, and a pump 44 and a filter 46 installed in the circulation route 42.