PROBLEM TO BE SOLVED: To provide a hydroponic system using no soil for easily and surely killing fungi in the nutritious liquid. SOLUTION: This hydroponic system works as follows: the nutritious liquid passed through culture tanks 1 is collected into an effluent tank 2, subjected to pressure treatment during passage through a pressure tank 4, and mixed with a nutritious stock liquid from a relevant tank 6 in a mixing tank 5, and then returned into the culture tank 1. Owing to the pressure treatment, fungi in the nutritious liquid undergo high-pressure liquid action and are surely killed, and the related equipment in contact with the nutritious liquid can be sterilized simultaneously as well. In this system, since there remains no chemical agent such as a fungicide, human health and the environment are never affected at all.
