In a flow rate estimation method of a blood pump, a general flow rate estimation formula which includes a correction term is formed based on a plurality of blood pumps. Measured data obtained from an objective blood pump implanted inside a patient is substituted into the correction term, thus forming a flow rate estimation formula of the objective blood pump. The flow rate Q of the objective blood pump is estimated based on the flow rate estimation formula and the values of the rotational speed N and the consumption current I of the motor of the objective blood pump, and the attribute data Z of the blood of the patient.