A hydroponics device, comprising: a cultivation tank that constitutes a flow channel through which a nutrient solution to be supplied to a plant flows; a nutrient solution tank that reserves the nutrient solution; a supply flow channel that guides the nutrient solution from the nutrient solution tank to the cultivation tank; a discharge flow channel that guides the nutrient solution from the cultivation tank to the nutrient solution tank; a pump that circulates the nutrient solution between the nutrient solution tank and the cultivation tank by way of the supply flow channel and the discharge flow channel, and a support unit provided in the cultivation tank and configured to support an underground part of the plant, wherein the supply flow channel has a ventilation path that allows an external space of the supply flow channel and an internal space of the supply flow channel to communicate with each other, the ventilation path inhibits a variation in a flow rate of the nutrient solution flowing into the cultivation tank from the supply flow channel, characterised in that a plurality of the cultivation tanks is provided, the supply flow channel includes a trunk flow channel and a plurality of branch flow channels branched from the trunk flow channel to guide the nutrient solution by the pump from the nutrient solution tank to each of the plurality of the cultivation tanks, the support unit has a root through-hole provided such that the root extending from the plant reaches the nutrient solution and has a flow channel through-hole provided such that a tip end portion of the supply flow channel is inserted therein, the ventilation path is provided at each tip end of the plurality of the branch flow channels and is a clearance between the branch flow channel and a tip end flow channel having a diameter greater than that of the branch flow channel, the branch flow channel and the tip end flow channel constitute the supply flow channel, the tip end flow channel constituting the tip end portion of the supply flow channel is inserted in the flow channel through-hole, and a lower end portion of the tip end flow channel is inserted in the nutrient solution with the lower end portion of the tip end flow channel positioned at a predetermined distance from a bottom surface of the cultivation tank. a cultivation tank that constitutes a flow channel through which a nutrient solution to be supplied to a plant flows; a nutrient solution tank that reserves the nutrient solution; a supply flow channel that guides the nutrient solution from the nutrient solution tank to the cultivation tank; a discharge flow channel that guides the nutrient solution from the cultivation tank to the nutrient solution tank; a pump that circulates the nutrient solution between the nutrient solution tank and the cultivation tank by way of the supply flow channel and the discharge flow channel, and a support unit provided in the cultivation tank and configured to support an underground part of the plant, wherein the supply flow channel has a ventilation path that allows an external space of the supply flow channel and an internal space of the supply flow channel to communicate with each other, the ventilation path inhibits a variation in a flow rate of the nutrient solution flowing into the cultivation tank from the supply flow channel, characterised in that a plurality of the cultivation tanks is provided, the supply flow channel includes a trunk flow channel and a plurality of branch flow channels branched from the trunk flow channel to guide the nutrient solution by the pump from the nutrient solution tank to each of the plurality of the cultivation tanks, the support unit has a root through-hole provided such that the root extending from the plant reaches the nutrient solution and has a flow channel through-hole provided such that a tip end portion of the supply flow channel is inserted therein, the ventilation path is provided at each tip end of the plurality of the branch flow channels and is a clearance between the branch flow channel and a tip end flow channel having a diameter greater than that of the branch flow channel, the branch flow channel and the tip end flow channel constitute the supply flow channel, the tip end flow channel constituting the tip end portion of the supply flow channel is inserted in the flow channel through-hole, and a lower end portion of the tip end flow channel is inserted in the nutrient solution with the lower end portion of the tip end flow channel positioned at a predetermined distance from a bottom surface of the cultivation tank.