To provide a pump which can operate a delicate behavior fluid such as a blood and is efficient at liquid pressure and is efficient on power.

The blood pump has a pump housing 110 for defining a pump chamber 112 having an inlet port 114 and an outlet port 116; a rotor 120 arranged in the pump housing; and an axial magnetic bearing arranged in the pump chamber and at least partially supporting the rotor. The axial magnetic bearing is formed with interaction between a spindle magnet assembly 160 arranged in a first spindle and a rotor magnet assembly 180 retained by the rotor. A setting screw 134 can be adjusted in a major axis direction of a shaft section of the axial magnetic bearing by moving the spindle magnet assembly along the major axis of the spindle.