Flotation tests of molydenite, chalcopyrite and cosalite were carried out by Hallimond tube with various xanthates and depressing agents. Molybdenite and cosalite showed that they have maximum flotability at about pH 6.0 while chalcopyrite has at pH 4.0-8.0 range. Oxidizing reagent, potassium permanganate is effective depressant of chalcopyrite on the selective flotation of molybdenite and chalcopyrite. On the other hand, potassium dichromate depresses cosalite on the selective flotation of molybdenite and cosalite or chalcopyrite and cosalite.