To provide a flush type simple toilet, which can be installed even at a place, where there is no potable-water and sewage waterway, and in which water used for flushing, washing or the like is circulated and can be used independently.

Sewage discharged from a stool is aerated by sufficiently blowing in air by a compressor 28 in an aeration tank 27, and organic matter is decomposed by aerobic bacteria. Sewage is made to flow into a tank 31 in which an air-permeable vessel is filled with bio-chips from an upper section and dripped, and the decomposition of organic matter is further promoted while solid organic matter such as a fibrous substance is detained among the chips and decomposed by microbes. Sewage is led to pass through a decoloring layer for making water seemingly colorless. Activated carbon is used as a decolorant in the decoloring layer but an inorganic material such as zeolite can also be used. Treated water is stored in a water storage tank 21, and reused as flushing water.