A garbage disposing device includes a treatment chamber used to decompose food wastes by a microorganism, intake passage, exhaust passage, and a return path extending from a diverging portion in the exhaust passage to the treatment chamber. An exhaust airflow adjuster is provided at the diverging portion. A control unit controls the exhaust airflow adjuster such that after water and ammonia in an air exhausted from said treatment chamber are adsorbed by a dehumidifier provided in the exhaust passage, a part of the air is returned to the treatment chamber through the return path, and the remaining air is exhausted to the outside through a deodorizer. As a result, a small deodorizer is available, and the garbage disposing device can be small-sized as a whole. In addition, it is possible to save energy used for the decomposing treatment of the food wastes. In a regenerating operation for removing the adsorbed water and ammonia from the dehumidifier, the control unit controls the exhaust airflow adjuster such that the return path is closed at the diverging portion.