PROBLEM TO BE SOLVED: To utilize heat of a dialysis waste fluid for heating feeding water while preventing contamination by the dialysis waste fluid.SOLUTION: A feeding water heating device comprises a primary side water-refrigerant heat exchanger, a secondary side water-refrigerant heat exchanger and a heat pump to heat feeding water supplied for a dialysis equipment side. The primary side water-refrigerant heat exchanger collects heat from a dialysis waste fluid by the heat exchange between a first refrigerant which is gas in ordinary temperature and normal pressure and the dialysis waste fluid discharged from a dialyzer. The secondary side water-refrigerant heat exchanger heats the feeding water by the heat exchange between the feeding water and a second refrigerant which is gas in ordinary temperature and normal pressure. A primary side refrigerant-refrigerant heat exchanger of the heat pump is linked to the primary side water-refrigerant heat exchanger through a primary side refrigerant piping. A secondary side refrigerant-refrigerant heat exchanger of the heat pump is linked to the secondary side water-refrigerant heat exchanger through a secondary side refrigerant piping.
