A blood purification apparatus includes a blood circuit, a blood purifying device, a driving device, an air bubble detection device, and a connection condition evaluation device. The blood circuit is provided with arterial and venous blood circuits, to which needles are attached at ends thereof. The blood purifying device is connected between the arterial and venous circuits. In a blood purifying treatment after a priming operation, the driving device drives the blood in the arterial blood circuit in a forward direction, and drives the blood in the venous blood circuit in a reverse direction. The air bubble detection device detects air bubbles in a liquid flowing in the arterial and venous blood circuits. The connection condition evaluation device evaluates connection conditions of the needles to the ends of the arterial and venous blood circuits based on the detection by the air bubble detection device.