A ventricular assist blood pump includes: a rotary part, a base part, and a housing. A value obtained by dividing an outer profile volume of the rotary part by a rotary volume of the rotary part is from 0.1 to 0.4. Assuming a volume which is a portion of a volume of a pump chamber and is disposed on a side where the rotary part exists obtained by partitioning by a predetermined plane P as a pump chamber main volume, a value obtained by dividing a rotary volume of the rotary part by the pump chamber main volume is from 0.4 to 0.7. A numerical value obtained by dividing the outer profile volume of the rotary part by the pump chamber main volume is from 0.05 to 0.2.
