<;P>;PROBLEM TO BE SOLVED: To provide an appropriate part environment control system suiting for a plant condition, based on a speaking plant approach idea. <;P>;SOLUTION: A device for discharging minute water drops to parts of cultivated plants includes a fog nozzle 5 discharging minute water drops to parts of cultivated plants, a controller 7 controlling the discharge of minute water drops, and a solar radiation sensor 10. Solar radiation data are accumulated at a prescribed time with the solar radiation sensor 10, and minute water drops are discharged when the accumulated amount of solar radiation exceeds a threshold value. <;P>;COPYRIGHT: (C)2011,JPO&INPIT