A blood purification apparatus is provided that can easily and accurately determine before treatment whether or not blocking of liquid by a check valve (18) is appropriate. In the blood purification apparatus including a blood circuit, a dialyzer (1), a dialysate introduction line (L1) and a dialysate discharge line (L2), pressure detection device (± to ³), a dialysate extraction device (10), a dialysate supply line (La), and a check valve (18) that blocks flow of a liquid from the blood circuit to the dialysate introduction line (L1), there are provided a control means (19) that makes it possible to generate a pressure difference between a side of the blood circuit and a side of the dialysate introduction line (L1) across the check valve (18), a monitor means (20) that makes it possible to monitor a change in a detection value of the pressure detection device based on the pressure difference, and a determination means (21) that makes it possible to determine whether or not blocking of liquid by the check valve (18) is appropriate based on the change in the detection value of the pressure detection device.
