PURPOSE: To provide a highly reliable hemodialyzer to a patient by improving problems of a degrading in dialysis efficiency owing to an intermittent flow, a deterioration in mechanism components die to a frequent action of a partition, balance error of a uniform flow rate circuit and the like when the uniform flow rate circuit in the supply and drain of a liquid is formed with a constant amount pump separated into two chambers with the partition in a water removing control of the hemodialyzer.

CONSTITUTION: Constant amount pumps 11 and 15 each separated into two chambers with a partition are connected to two cascades and a front stage- constant amount pump 11 and a rear stage constant amount pump 15 are driven in an opposite phase. Thus, an intermittent flow with the front stage pump is turned to a continuous flow with the rear stage pump to supply an dialysis solution to a dialyzer.