To commonly use one fan in an air circulating system for circulating the air in a decomposing tank and an air ventilating system for ventilating the air in the tank.

The refuse treating apparatus comprises a decomposing tank 3 for decomposing a raw refuse by containing the refuse, a fan 29 for circulating the air in the tank 3 by forward or reverse rotation or ventilating the air in the tank 3, and a valve mechanism 30 for selecting a flowing route for operating by the forward or reverse rotation. In the case of circulating the air in the tank 3, the route of the air input into the tank 3 out of the tank 3 is shut OFF by the mechanism 30 by the forward rotation of the fan 29, and the air is fed in the tank 3 b the fan 29. In the case of ventilating the air in the tank 3, the route of the air circulated in the tank 3 is shut OFF b the mechanism 30 by reverse rotation of the fan 29, and the air in the tank 3 is replaced by the air out of the tank 3 by the fan 29.