Abstract: A new method for preparation of organic compost by incorporating zeolite into excretions from domestic animals. In the method, zeolite of about 10 to 30% relative to the total weight of excretions is homogeneously mixed and then piled for a predetermined period so that the water content of a surface portion of the pile of the mixture decreases to about 25% by weight or less, and the average water content of the entire pile decreases to about 55% by weight or less. The piled mixture is then supplied to a fermentation vessel in which it is scooped and turned over such that a high water content portion inside the low water content surface portion is divided into small masses and the low water content surface portion is divided into fine powders, so that the fine powders are spread around the small masses to thereby achieve effective aerobic fermentation in the vessel.