A blood purification apparatus that includes a blood circuit to a distal end of which a puncture needle (a, b) is connectable and through which blood of a patient is extracorporeally circulate; and a blood purification device that is configured to purify the blood flowing in the blood circuit, the blood purification apparatus being capable of performing blood purification treatment through the blood purification device while extracorporeally circulating the blood of the patient through the blood circuit with the puncture needle (a, b) being stuck in an access vessel of the patient, characterized in that the blood purification apparatus comprising: a pressure-change-producing device configured to apply a positive pressure or a negative pressure to a distal portion of the blood circuit while the puncture needle (a, b) is yet to be connected to the blood circuit; a pressure-change-detecting device configured to detect a pressure change in the distal portion of the blood circuit that occurs when the distal portion of the blood circuit that is under the positive pressure or the negative pressure applied by the pressure-change-producing device is being connected to the puncture needle (a, b) that is stuck in the patient; and an evaluation device configured to evaluate a state of sticking of the puncture needle (a, b) on the basis of the pressure change detected by the pressure-change-detecting device. a blood circuit to a distal end of which a puncture needle (a, b) is connectable and through which blood of a patient is extracorporeally circulate; and a blood purification device that is configured to purify the blood flowing in the blood circuit, the blood purification apparatus being capable of performing blood purification treatment through the blood purification device while extracorporeally circulating the blood of the patient through the blood circuit with the puncture needle (a, b) being stuck in an access vessel of the patient, characterized in that the blood purification apparatus comprising: a pressure-change-producing device configured to apply a positive pressure or a negative pressure to a distal portion of the blood circuit while the puncture needle (a, b) is yet to be connected to the blood circuit; a pressure-change-detecting device configured to detect a pressure change in the distal portion of the blood circuit that occurs when the distal portion of the blood circuit that is under the positive pressure or the negative pressure applied by the pressure-change-producing device is being connected to the puncture needle (a, b) that is stuck in the patient; and an evaluation device configured to evaluate a state of sticking of the puncture needle (a, b) on the basis of the pressure change detected by the pressure-change-detecting device. a pressure-change-producing device configured to apply a positive pressure or a negative pressure to a distal portion of the blood circuit while the puncture needle (a, b) is yet to be connected to the blood circuit; a pressure-change-detecting device configured to detect a pressure change in the distal portion of the blood circuit that occurs when the distal portion of the blood circuit that is under the positive pressure or the negative pressure applied by the pressure-change-producing device is being connected to the puncture needle (a, b) that is stuck in the patient; and an evaluation device configured to evaluate a state of sticking of the puncture needle (a, b) on the basis of the pressure change detected by the pressure-change-detecting device.