PROBLEM TO BE SOLVED: To provide an environmental control device of a greenhouse which is capable of improving growth efficiency by performing humidity control in addition to temperature control.SOLUTION: An environmental control device of a greenhouse comprises: a temperature sensor 13 that detects a temperature in the greenhouse 1； a humidity sensor 14 that detects a humidity in the greenhouse 1； an air conditioning chamber 6 provided with a cooling pad 10 that is maintained at a wet state based on supply of water from a water-supply system； a plurality of windows 9a, 9b, 9d which are provided in the air conditioning chamber 6, and select between a state where the cooling pad 10 is positioned at a circulation path of air in the greenhouse 1 and a state where outside air to be taken in from the outside of the greenhouse 1 is guided into the greenhouse 1 via the cooling pad 10； and a controller 5 that, when air in the greenhouse 1 is at a temperature that does not require cooling, controls the plurality of windows 9a,9b,9d such that air to be guided into the greenhouse 1 passes through the cooling pad 10 to adjust the humidity of air to be guided into the greenhouse 1.【課題】温度管理に加えて湿度管理を行って育成効率を向上させ得る温室の環境制御装置を提供する。【解決手段】温室１内の気温を検出する温度センサ１３と、温室１内の湿度を検出する湿度センサ１４と、給水装置からの水の供給に基づいて、湿潤状態に維持されるクーリングパッド１０を備えた空調室６と、空調室６に設けられ、温室１内の空気の循環経路にクーリングパッド１０を位置させる状態と、温室１外から取り入れられる外気を、クーリングパッド１０を介して温室１内に案内する状態とを選択する複数の窓９ａ，９ｂ，９ｄと、温室１内の空気が冷房を要しない気温である時、温室１内に案内される空気がクーリングパッド１０を通過するように複数の窓９ａ，９ｂ，９ｄを制御して、温室１内に案内する空気の湿度を調整するコントローラー５を備えた。【選択図】図１
