Unburned carbon flotation is performed to investigate the separation efficiency of the collector containing poly unsaturated fatty acid on the bottom ash. The results of an experiment using soybean oil collector (S.O. collector) show the high recovery and enrichment ratio at the dosage of 9 kg/ton. In order to investigate the collector efficiency on poly unsaturated fatty acids, a collector is manufactured using the esterification reaction. Unsaturated fatty acid oil collector (U.F.O. collector) is manufactured in which removed saturated fatty acids and increased content of poly unsaturated fatty acid from the S.O. collector. The U.F.O. collector is showed high separation efficiency at 7 kg/ton. The U.F.O. collector concentrates the unburned carbon content of the concentrate and improves the recovery with a low dosage than the S.O. collector. By removing saturated fatty acids and increasing the content of unsaturated fatty acids, this investigation provides that 1) the dosage of a collector can be reduced up to 2 kg/ton difference, and 2) the poly unsaturated fatty acids shows the best performance for adsorption properties on the unburned carbon surface.