PROBLEM TO BE SOLVED: To provide a technology to feed a peritoneal dialysis fluid more accurately.SOLUTION: A peritoneal dialyzer for heating a dialysis fluid supplied from a dialysate bag in a heating part, and injecting the heated dialysis fluid in the abdominal cavity includes: pre-treatment means for executing control so as to move at least a part of the dialysis fluid present in the heating part to a predetermined place other than the heating part (except for the injection in the abdominal cavity) after the completion of at least one of a priming operation to press a diaphragm pump and fill the heating part with the dialysis fluid and a leak check operation to check leakage of the dialysis fluid in a fluid feeding channel from the diaphragm to the heating part； and fluid feeding means for executing control to start the injection of the dialysis fluid in the abdominal cavity through the heating part after the movement by the pre-treatment means.SELECTED DRAWING: Figure 1
