Abstract: Particles contained in a suspension are separated in accordance with their magnetic susceptibility and based on the variation in flow velocity of suspension. In order to achieve this magnetic separation, a pair of wall plates having at least one flat surface in which a plurality of ferromagnetic narrow wires are buried in parallel are positioned in parallel to each other with a small distance therebetween so that the flat surfaces are opposed to each other to form a channel. The suspension flows in a laminar state with different flow velocities through the channel in the longitudinal direction of the ferromagnetic wires. A magnetic field is externally applied to the channel in the direction perpendicular both to the flow direction and the wall plates. Particles are separated in accordance with their magnetic susceptibility and based on variation in flow velocity which interacts with the magnetic susceptibility.