PROBLEM TO BE SOLVED: To provide a hemodialysis device which complements both demerits of a back-filtration system and an on-line system, can control appropriately even when UFR (ultrafiltration rate) is low or clogging is caused, and is not troublesome and is inexpensive.SOLUTION: During a back-filtration operation of activating a dewatering/back-filtration pump, when a dialysis fluid pressure sensor detects that an increase degree of a dialysis fluid pressure is equal to a predetermined value or larger, a control device switches to an on-line operation of feeding the dialysis fluid from a fluid feeding line.
