PROBLEM TO BE SOLVED: To facilitate maintenance of a composting device. SOLUTION: The composting device of this invention which supplies air to a composting material from a ventilating hole provided at a ventilation pipe 24 is characterized by being provided with a granular layer which is disposed around the ventilation pipe 24 and is composed of spacers 26 being larger than the ventilating hole of the ventilation pipe 24 and with a compost supporting layer 29 which is disposed between the granular layer and the composting material, has a structure hardly allowing the composting material to pass through and has air permeability. Thereby even when composting material of large water content such as cattle excrement is used, the ventilation pipe 24 generates no clogging and clogging is generated in the compost supporting layer 29. Accordingly, when ventilation inferiority is generated, only the compost supporting layer 29 is necessary to be repaired while the ventilation pipe 24 is held as it is.
