A method of hydroponically cultivating a plant wherein a nutrient solution is supplied under careful control depending on the growth conditions of the plant so that the nutritional state of the plant can be improved and the total usage of the nutrient solution can be reduced, which comprises: cultivating the plant without replenishing a fresh nutrient solution at an initial cultivation stage； continuing the cultivation with the fresh nutrient solution replenished by an amount compensating for the spontaneous loss in the nutrient solution at a medium cultivation stage； and then conducting the cultivation with supplying the fresh nutrient solution by an amount exceeding the spontaneous loss in the nutrient solution at a later cultivation stage. The amount of the nutrient solution replenished at the later cultivation stage is increased as the cultivation proceeds.
