A blood pump of the disposable type for substituting for the blood circulation function of the heart or supplementing the same in which a less expensive material is employed and the durability is improved. In an impeller (2) located within a blood pump (1), at least one of the shaft (20) and a bearing (62) holding the shaft (20) is made of a high-density polyethylene having a molecular weight of from 5 to 80x104 and the sliding part thereof is coated with a polymer film (64) having a hydrophilic group. It is preferable that the polymer film (64) having a hydrophilic group has a water contact angle of 50° or less and an initial torque of 1.0 Nm or less.
