The present invention provides a
blood pump capable of substantially completely preventing
thrombus from attaching to the inner bottom portion of the casing without lowering the anti-hemolytic characteristic of blood. A
centrifugal blood pump in accordance with the present invention comprises a pump casing, a suction inlet disposed at the central portion on the upper side of the casing, a delivery outlet disposed at the bottom
peripheral portion of the casing, a main
impeller (D in
diameter) for forming a centrifugal flow of blood supplied from the suction inlet in the range from the central portion to the
peripheral portion to feed the blood to the delivery outlet, wherein the main
impeller is provided with an stirring
impeller, the surface of which is provided with one or more stirring elements (L in entire length) having the shape of a fin or a groove, and the dimensions of the stirring elements are determined to satisfy inequality (1): 0.43<LD<1.30 and inequality (2) 0.03<S / A<0.21, where S is the surface area of the blood contact surfaces of the stirring elements.