a magnetic separation apparatus , comprising : a separation tank to which wastewater containing flocculated magnetic flocs is supplied ; a disk - shaped or a drum - shaped separator that adsorbs the magnetic flocs with magnetic force while being rotated , the separator being arranged in the separation tank ; and a collection device that collects the magnetic flocs adsorbed by the separator , wherein the improvement comprises that a rotational direction of the separator in the wastewater in the separation tank is set to be the same as a flow direction of the wastewater flowing in the separation tank as well as a lower portion of the separator being under the wastewater in the separation tank .