PROBLEM TO BE SOLVED: To provide artificial breeding water suitable for breeding of both of fresh water fishes and sea water fishes instead of natural water and natural sea water. SOLUTION: This breeding water suitable for the artificial breeding of both sea water organisms and fresh water organisms is provided by adding at least sodium, calcium and potassium into the breeding water so that each of the adding amounts becomes≥0.0951 [g/l] and≤0.380 [g/l] potassium,≥0.0993 [g/l] and≤0.401 [g/l] calcium, and≥2.777 [g/l] and≤10.656 [g/l] sodium. COPYRIGHT: (C)2011,JPO&INPIT