A hydroponic apparatus includes: a cultivation tank (1) inside which a plant (P) is held, and into a lower portion of which a nutrient solution (F) is introduced； a separator (4) that separates a first space (D1) where aboveground portions (P1) of the plant (P) are positioned and a second space (D2) where underground portions (P2) of the plant (P) are positioned； an environmental control unit (81) that performs control of adjusting a temperature of the first space (D1) to a first temperature in a first period and adjusting the temperature of the first space to a second temperature lower than the first temperature in a second period； and a humidity control unit (83) that performs control to decrease a humidity of the second space when the growing period for the plant shifts from the first period to the second period.
