A method for separating magnetic particles dispersed in a fluid by magnetic attraction, characterized in that an object fluid in which magnetic particles are dispersed is passed through a magnetized rotary tube, magnetic particles are made to adhere by magnetic attraction to the magnetized surface in the tube, the flow of the fluid is suspended before the capacity of magnetic attraction of the tube lowers, the magnetized surface is demagnetized, an exhaust fluid for exhausting magnetic particles in the tube is made to flow under pressure through the tube, the exhaust fluid mixed with magnetic particles is discharged, and the magnetic particles are separated from the exhaust fluid.
