PROBLEM TO BE SOLVED: To feed a dialysis solution from a dialysis solution circuit side to a blood circuit side, and to discharge the solution from the blood circuit side to the dialysis solution circuit side through a membrane of a dialyzer by a simple device structure.SOLUTION: The hemodialyzer 1 includes: a measuring container 40 including a displaceable partition wall 52 which divides the interior into a first chamber 50 and a second chamber 51 an inflatable/deflatable first circuit 41 for feeding the dialysis solution in the first chamber 50 into a dialyzer 10 an inflatable/deflatable second circuit 52 for discharging the dialysis solution in the dialyzer 10 into the second chamber 51 an opening/closing valve 62 for opening/closing the first circuit 41 and an opening/closing valve 70 for opening/closing the second circuit 42. When the partition wall 52 is displaced to the first chamber 50 side filled with the dialysis solution to feed the dialysis solution in the first chamber 50 into the dialyzer 10 through the first circuit 41 to discharge the dialysis solution in the dialyzer 10 into the second chamber 51 through the second circuit 42, the first circuit 41 is opened by the opening/closing valve 62, while the second circuit 42 is closed by the opening/closing valve 70 and the second circuit 42 is opened by the opening/closing valve 70.
