To provide a working liquid cleaning system capable of removing fine matters in line reliably.

A working liquid cleaning system comprises a supply tank 1 storing a working liquid, a circulation path 3 supplying the working fluid to a processing apparatus 2 and returning the working liquid used in the processing to the supply tank so as to circulate, a circulation pump 4 arranged in the circulation path 3 and supplying the working liquid to the processing apparatus 2 and a centrifugal separator 5 separating and removing fine matter included in the working liquid from the working liquid used in the process by centrifugal force. In the centrifugal separator 5, the input side 5a for the working liquid is connected to the side of the circulation pump, and the output side 5b for the working liquid after separation of fine matter is connected to the side of the processing apparatus. In the output side for the working liquid, a working liquid supply adjusting mechanism 6 is provided.