To provide a culture system by which a max. production quantity is secured through the used of a circulation filtering method.

In the culture system adopting the circulation filtering system, the growth process of culture objects is divided into n(n=5) stages, (n-1)-pair of units (four units) including the m-groups (M=2) of water tanks A and B are provided, the culture object is reared in one water tank A, a part of the culture objects in the water tank A are transferred to the other water tank B in a succeeding stage so as to rear the culture objects in the tanks A and B, a part of the culture objects in the tank A are shipped in the succeeding stage, the culture objects in the tank B are shipped in the next stage and the culture objects in the water tank A are shipped in the final stage. A series of these processes are executed by being deviated by one stage in terms of a time concerning the respective units. After that, the water tank A or B which becomes vacant since the culture objects are shipped in the respective units are used for the next process so that the series of processes for executing them are executed by a deviation by one stage in terms of a time concerning the respective units. After that, the m×(n-1) (=2×4=8)-number of water tanks are supplied for rearing the culture objects by using the tanks A or B which becomes vacant since the culture objects are shipped in the respective units in the succeeding processes.