PROBLEM TO BE SOLVED: To provide a hydroponic apparatus with which the liquid level of a cultivation bed can be moved up and down without using motive energy, and also which continues to reliably operates in a simple structure without using any small activating parts such as a float valve mechanism.SOLUTION: The hydroponic apparatus includes: a cultivation bed 3 a culture liquid bath 7 an air-tight culture liquid tank 11 in the inner part of which the culture liquid can be retained an atmosphere-introducing passage 17 for introducing atmosphere into the culture liquid tank 11 when the liquid level of the cultivation bed 3 is lower than the lowest liquid level a dam part 21 making the culture liquid which flows down to the culture liquid bath 7 from an outflow port 19, flow out to the cultivation bed 3 at a prescribed level of outflowing liquid and outflow passage 23 making the culture liquid in the culture liquid bath 7 leak out little by little to the cultivation bed 3 by the gravity.COPYRIGHT: (C)2011,JPO&INPIT【課題】動力を用いることなしに栽培ベッドの液位を昇降させることができるだけでなく、フロート弁機構等の小さな作動部品を一切用いることなく、簡素な構成により確実に作動しつづける水耕栽培装置を提供する。【解決手段】栽培ベッド3と、養液槽7と、内部に養液を保持可能な気密性を有する養液タンク11と、前記栽培ベッド3の液位が前記最低液位を下回った場合に前記養液タンク11内に大気を導入するための大気導入路17と、流出口19から前記養液槽7に流下した養液を所定の溢出液位において前記栽培ベッド3に溢れさせる堰部21と、前記養液槽7内の養液を重力により少しずつ前記栽培ベッド3に漏出させる漏出流路23とを具備してなる。【選択図】図3
