Disclosed is an apparatus having a heating function for hemodialysis, hemodiafiltration, hemofiltration or peritoneal dialysis, wherein the apparatus includes at least one of pipe for transferring at least one fluid of blood and dialsate, and a heating unit for heating at least one fluid of blood and dialsate, wherein the fluids to be heated by the heating unit are substances to be injected into human body and the heating unit is arranged for measuring flow rates of the fluids to be heated, and injecting temperatures related with the flow rate to heat the fluids to be heated. The heating unit comprises: flow passages through which the fluids to be heated are flowed a heater formed as a part of the flow passages, for generating heat and a cover means including a first connection portion through which the fluids enter the flow passages, and a second connection portion through which the fluids come out from the flow passages. Present invention provides one effect in that blood having the same or nearly same temperature as that of human body can be injected into human body to prevent side effects caused by the dialysis and another effect in that blood can be heated effectively because the shapes of flow passages around the heater is deformed in improved manner.
