A method of manufacturing a catalyst for reacting transesterification of an animal.vegetable oil is provided to generate waste water including an inorganic salt by a corecipitation method by manufacturing the catalyst for reacting transesterification of the animal.vegetable oil by a milling method and to have a simple manufacturing step. Precursor slurry is manufactured by performing milling after dispersing a precursor by water. The precursor is separated from the precursor slurry and dried. A transesterification catalyst is obtained by heat-treating the dried precursor. The milling is a ball-mill, a dynomill or a sand mill. The precursor is a magnesium precursor which is a magnesium hydroxide, a magnesium oxide, a magnesium carbonate or a mixture thereof. The transesterification catalyst includes: an aluminium hydroxide, an aluminium oxide, an aluminum carbonate or an aluminum precursor which is a mixture thereof; and a zinc hydroxide, the zinc oxide, a zinc carbonate or a zinc precursor which is a mixture
