A centrifugal blood pump apparatus includes an impeller provided in a blood chamber, a plurality of permanent magnets provided in the impeller, and a plurality of sets of magnetic materials and coils provided in a motor chamber for driving the impeller to rotate with a diaphragm interposed therebetween. The plurality of permanent magnets are aligned with a gap therebetween in a rotation direction of the impeller. Accordingly, if the weight of the permanent magnets is maintained at a constant value, a magnetic field can be strengthened even with a wide motor gap due to the diaphragm, as compared to an example where there is no gap between the permanent magnets.