A blood purification apparatus comprising: a blood circuit including an arterial blood circuit and a venous blood circuit and allowing a patient's blood to extracorporeally circulate from a distal end of the arterial blood circuit to a distal end of the venous blood circuit; a blood purification unit connected to a proximal end of the arterial blood circuit and to a proximal end of the venous blood circuit and configured to purify the blood flowing through the blood circuit; a squeezable tube connected to the arterial blood circuit; a blood pump formed of a peristaltic pump configured to deliver liquid by squeezing, with a roller, the squeezable tube while a rotor is driven to rotate, the blood pump delivering the liquid from the distal end of the arterial blood circuit toward the blood purification unit when the rotor is rotated normally such that the roller moves in a lengthwise direction of the squeezable tube, the blood pump delivering the liquid from the blood purification unit toward the distal end of the arterial blood circuit when the rotor is rotated reversely such that the roller moves in the lengthwise direction of the squeezable tube; a discharge unit through which a priming solution supplied into the blood circuit is allowed to be discharged to an outside; a closing unit configured to generate a negative pressure in the squeezable tube at the normal rotation of the rotor of the blood pump by closing a region of the blood pump that is filled with the priming solution; and a control unit configured to control the blood pump and the closing unit, characterized in that the control unit is configured to execute a priming step in which the priming solution supplied into the blood circuit is discharged through the discharge unit while a flow route in the blood circuit is filled with the priming solution; a normal rotation step in which, after the priming step, the region filled with the priming solution is closed by the closing unit, and the rotor of the blood pump is rotated normally until the roller of the blood pump releases the squeezable tube to generate a backflow; a reverse rotation step in which, after the backflow is generated in the normal rotation step at the release of the squeezable tube by the roller of the blood pump, bubbles are moved by reversely rotating the rotor while disabling the closing by the closing unit; and a discharge step in which the bubbles moved in the reverse rotation step are discharged through the discharge unit. a blood circuit including an arterial blood circuit and a venous blood circuit and allowing a patient's blood to extracorporeally circulate from a distal end of the arterial blood circuit to a distal end of the venous blood circuit; a blood purification unit connected to a proximal end of the arterial blood circuit and to a proximal end of the venous blood circuit and configured to purify the blood flowing through the blood circuit; a squeezable tube connected to the arterial blood circuit; a blood pump formed of a peristaltic pump configured to deliver liquid by squeezing, with a roller, the squeezable tube while a rotor is driven to rotate, the blood pump delivering the liquid from the distal end of the arterial blood circuit toward the blood purification unit when the rotor is rotated normally such that the roller moves in a lengthwise direction of the squeezable tube, the blood pump delivering the liquid from the blood purification unit toward the distal end of the arterial blood circuit when the rotor is rotated reversely such that the roller moves in the lengthwise direction of the squeezable tube; a discharge unit through which a priming solution supplied into the blood circuit is allowed to be discharged to an outside; a closing unit configured to generate a negative pressure in the squeezable tube at the normal rotation of the rotor of the blood pump by closing a region of the blood pump that is filled with the priming solution; and a control unit configured to control the blood pump and the closing unit, characterized in that the control unit is configured to execute a priming step in which the priming solution supplied into the blood circuit is discharged through the discharge unit while a flow route in the blood circuit is filled with the priming solution; a normal rotation step in which, after the priming step, the region filled with the priming solution is closed by the closing unit, and the rotor of the blood pump is rotated normally until the roller of the blood pump releases the squeezable tube to generate a backflow; a reverse rotation step in which, after the backflow is generated in the normal rotation step at the release of the squeezable tube by the roller of the blood pump, bubbles are moved by reversely rotating the rotor while disabling the closing by the closing unit; and a discharge step in which the bubbles moved in the reverse rotation step are discharged through the discharge unit.