To grow a plant which stores nutrients synthesized in an above-ground part into an underground part, a hydroponic cultivation apparatus waters the underground part. The hydroponic cultivation apparatus includes: a void portion housing the underground part while establishing a substantially sealed state； a sensor which detects an amount of moisture in the void portion at the underground part or around the underground part； an air conditioning fan which introduces outside air to the void portion and controls temperature and humidity inside the void portion； and a controller which controls the amount of moisture detected by the sensor by driving the air conditioning fan in such a way as to adjust an amount of the outside air or an introduction period of the outside air.
