PROBLEM TO BE SOLVED: To prevent curtains from being caught by a drive rope or the like even if strong wind blows into a greenhouse.SOLUTION: Whether or not wind speed of wind observation data outside a greenhouse, which is measured by an outside climate sensor 500, is a set value or more is determined, and an opening/closing operation of curtains 110, 120 installed in the greenhouse is controlled according to the wind speed outside the greenhouse. The opening/closing operation of the curtains 110, 120 installed in the greenhouse is usually controlled according to temperature in the greenhouse, a sunlight condition or the like. According to the present invention, even in the case where wind having a predetermined or more wind speed blows outside the greenhouse, the opening/closing operation of the curtains 110, 120 can be quickly regulated. Therefore, even if wind having the predetermined or more wind speed blowing outside the greenhouse blows in from ventilation windows, a curtain opening/closing apparatus 1
