Provided are a dialysis device and a control method that are capable of removing water in a volume proportional to body weight at a predetermined water removal rate irrespective of the embodiment of a replacement fluid. This dialysis device 100 is provided with: a blood circuit 110； a blood purification means 120； a dialysate circuit 130 having a dialysate delivery unit 133 that delivers a dialysate through the blood purification means 120 so as to perform fluid replacement by backfiltration or water removal； and a control unit 140 which performs control so as to cause the dialysate delivery unit 133 to carry out water removal from the blood circuit 110 and intermittent fluid replacement to the blood circuit 110. The time for performing fluid replacement is computed on the basis of a prescribed fluid replacement volume and a prescribed fluid replacement rate r. When fluid replacement is not being performed, water removal in a volume proportional to body weight is performed at a preset water removal rate f1, and at the same time, water removal in a volume proportional to recovered replacement fluid is performed at a replacement fluid recovery rate f2 based on a prescribed replacement fluid volume. When fluid replacement is being performed, fluid replacement is carried out at a backfiltration rate R that is computed by subtracting the preset water removal rate f1 from the prescribed fluid replacement rate r.L'invention concerne un dispositif de dialyse et un procédé de commande qui sont aptes à éliminer l'eau selon un volume proportionnel au poids corporel à un taux d'élimination d'eau prédéterminé, quel que soit le mode de réalisation d'un fluide de remplacement. Le dispositif de dialyse (100) est pourvu : d'un circuit sanguin (110) ； d'un moyen de purification de sang (120) ； d'un circuit de dialysat (130) possédant une unité de distribution de dialysat (133) qui distribue un dialysat à travers le moyen de purification de sang (120) de façon à effectuer un remplacem
