The present invention relates to an openable vinyl fixing device and a vinyl greenhouse. The openable vinyl fixing device enables easy opening and closing of an openable window formed on a roof. In contrast with the conventional fixed idea that when a vinyl opening operator (opener) is positioned at the lowermost end of vinyl, a vinyl supporting pipe does not completely unwind vinyl of a vinyl window, but slightly winds the vinyl, and the vinyl supporting pipe is positioned at the outer portion of the vinyl window, the present invention enables the vinyl to be completely unwound by rotating the vinyl supporting pipe a little bit more when closing the vinyl window, wherein the vinyl supporting pipe is positioned between an arc frame and the vinyl of the vinyl window to thereby form a space, and the vinyl supporting pipe is fixed in the space by means of the openable vinyl fixing device.
