To provide an apparatus for fermenting and treating organic matter in which organic matter is kept in a state suitable for aerobic fermentation, efficiently fermented, broken down and converted to compost.

In the apparatus 1 for fermenting and treating organic matter, organic matter 40 heaped up on the installation surface 2 is covered with a weather resistant protective sheet 10 having both air permeability and water proofing property and the four peripheral edges 11-14 of the protective sheet 10 are fixed on the installation surface 2 by cover weights 21-24. An exhaust flue 3 is protruded upward from the center of the heaped organic matter 40 and air supply tubes 61-64 are horizontally put in the organic matter 40 from the four corners of the protective sheet 10. Since the protective sheet 10 has prescribed air permeability and moisture permeability as well as weather resistance and water proofing property, the organic matter 40 is kept at a temperature and humidity suitable for aerobic fermentation and enough air for fermentation is also supplied. The fermentation and breakdown of the organic matter 40 are therefore facilitated and the organic matter 40 can be efficiently converted to compost.