To provide a producing apparatus of reclaimed water and a producing method of the reclaimed water by which a disinfectant can be effectively utilized by a simple method and thereby lowering of penetration performance and separation performance of a reverse osmosis membrane due to propagation of microorganisms or adhesion or the like of the microorganism and its metabolite on a reverse osmosis membrane surface can be effectively prevented.

Water to be treated is filtered by using a dipping type membrane filtration apparatus equipped with a filtration membrane which is arranged by dipping in a treating tank and which filters the water to be filtered and a filtered water tank for storing filtered water obtained by filtration of the water to be treated with the filtration membrane and then the filtered water obtained by filtration is sterilized and is subjected to reverse osmosis treatment using the reverse osmosis membrane. In this producing method of the reclaimed water, a part of concentrated water obtained by the reverse osmosis treatment is returned to the filtered water.