Abstract: Apparatus for opening and closing the flexible screen of a greenhouse or the like include an elongated driving shaft rotatably mounted about a fixed axis of rotation, a prime mover such as a reversible motor for selectively rotating the driving shaft in either one of the normal and reverse directions, transmission gear apparatus operatively connected to the driving shaft, an elongated flexible driving shaft operatively connected at one end to the transmission gear apparatus adapted to be rotated through the transmission gear apparatus upon the rotation of the driving shaft, reduction gear apparatus operatively connected to the other end of the elongated flexible driving shaft and a winding rod operatively connected at one end to the reduction gear apparatus and adapted to be rotated through the reduction gear apparatus upon rotation of the flexible driving shaft.