Disclosed is a vinyl greenhouse with a triangular top roof for ventilation including: a triangular frame which is disposed at the top of a roof of the vinyl greenhouse and has a front cross section in the form of � winding bars which are mounted at both inclined sides of the triangular frame side by side in the length direction of the vinyl greenhouse a cover which is fixed to the triangular frame and wound on the winding bars motor assemblies each of which is mounted to rotate the winding bar, so that the winding bar moves along the inclined side while winding the cover by rotation to open the triangular frame or moves along the inclined side in the reverse direction while releasing the cover by reverse rotation to shut the triangular frame and a guide member which is connected to the motor assembly in such a manner that an end of the guide member is hinge-coupled to a mounting place in order to guide the motor assembly to move together with the winding bar while rotating the winding bar. The vinyl greenhouse can make a worker conveniently move on the upper part of the vinyl greenhouse through the minimum installation of wires or rings, increases the lifespan of the vinyl greenhouse by preventing fixation of foreign matters on drainage pads, is easy to manage, is also easy to maintain and repair because a plastic covering can be replaced partially, provides structural stability because it is less vulnerable to wind, and brings fast heat exchange because a vinyl opening and shutting section is located at the top of the vinyl greenhouse.
