The hemodialysis device (1) is provided with: a dialyzer (2) for performing hemodialysis a blood circuit (3) that is connected to the dialyzer a dialysis solution circuit (4) that is connected to the dialyzer a replacement solution port (31) that is provided in the dialysis solution circuit and can be opened and closed using a cover member and a replacement solution passage (6), one end of which is connected to the blood circuit and the other end of which is connected to the replacement solution port. In order to remove the cover member from the replacement solution port to open the closed port and connect the replacement solution passage to the open replacement solution port after a dialysis solution exchange process of filling dialysis solution in the dialysis solution circuit, a negative pressure formation process for making the pressure inside the dialysis solution circuit negative is performed after the dialysis solution exchange process and then the replacement solution port is opened from a closed state. The method prevents the overflow of dialysis solution from the replacement solution port and allows work to be performed hygienically.Linvention concerne un dispositif dhémodialyse (1) qui est pourvu : dun dialyseur (2) qui permet deffectuer une hémodialyse dun circuit sanguin (3) qui est relié au dialyseur dun circuit de solution de dialyse (4) qui est relié au dialyseur dun orifice de solution de remplacement (31) qui est disposé dans le circuit de solution de dialyse et qui peut être ouvert et fermé à laide dun élément couvercle dun passage de solution de remplacement (6), dont une extrémité est reliée au circuit sanguin et dont lautre extrémité est reliée à lorifice de solution de remplacement. Afin de retirer lélément couvercle de lorifice de solution de remplacement pour ouvrir lorifice fermé et pour relier le passage de solution de remplacement à lorifice de solution de remplacement ouvert, après un processus déchange de solution de dialyse par le
