A hemodialysis apparatus 1 is provided with a dialyzer 2 for performing hemodialysis, a blood circuit 3 connected to the dialyzer, a dialysis solution circuit 4 connected to the dialyzer, a replacement fluid port 31 provided in the dialysis solution circuit and capable of being opened and closed by a lid member, and a replacement fluid passage 6 having its one end connected to the blood circuit and the other end connected to the replacement fluid port.