A blood purification apparatus is provided that is capable of detecting an abnormal state of puncture into a blood vessel with an arterial puncture needle or a venous puncture needle. The blood purification apparatus includes an oscillating device capable of supplying an alternating current at a predetermined frequency and changing the frequency of the alternating current among a plurality of frequencies, a measuring device capable of measuring an impedance for each of the frequencies, a calculating device capable of acquiring an impedance frequency characteristic, a storage device capable of storing an impedance frequency characteristic acquired in a case of normal puncture into the patient's blood vessel with an arterial puncture needle and a venous puncture needle, and an identifying device capable of identifying whether the puncture into the blood vessel with the arterial puncture needle a or the venous puncture needle b is normal in accordance with the change observed between the impedance frequency characteristic acquired by the calculating device and the impedance frequency characteristic stored in the storage device.
