To provide a blood purification apparatus in which whether or not the connection of a communicating line is appropriate can be determined more accurately. A blood purification apparatus includes a control device 16 that is capable of executing a pressure-applying step in which a negative pressure or a positive pressure is applied to a flow route of one of a tube section and a blood circuit； a propagating step in which the negative pressure or the positive pressure applied in the pressure-applying step is propagated to the flow route of an other of the tube section and the blood circuit through the communicating line； and a checking step in which whether or not the propagation of the negative pressure or the positive pressure in the propagating step is successful is checked with reference to the pressure detected by the pressure-detecting device, and in which whether or not the connection of the communicating line is appropriate is checked with reference to whether or not the propagation of the negative pressure or the positive pressure is successful.
