Abstract: 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.