To provide a blood pump with an improved impeller, which is usable in a vascular area without using a cannula.

In this blood pump 1 with the improved impeller, the blood pump 1 with a pump casing 7 and an electromechanical drive type impeller 10 placed in the casing 7 has at least two connectors 6, 8 directly placed in the pump casing 7 to connect blood vessel outside the heart, for instance, a suture ring 6 or a synthetic vascular graft, and the connectors are enabled to directly connect the blood vessel to the pump casing 7. This kind of pump can be embedded in the ascending aorta 3 to reduce a load on the left ventricle in the pulmonary artery trunk, or the bifurcation of the pulmonary artery trunk to reduce a load on the right ventricle, and other internal blood vessel to promote vascular flow or increase blood pressure in a specific blood vessel section to enable the pump to be embedded in a form of pump pipe.