PURPOSE: To enhance the workability by fitting the end of a plate member of a curtain wall and installing a zipper where a gasket outer face dimension is made smaller than an indoor sided-internal dimension.

CONSTITUTION: A gasket 5 is fixed with a mullion joint and transoms 4 and 41 while fixing frames 6 and 61 are inserted into an indoor side from outside and right and left parts and the upper part are fitted into the gasket 5. Then, a zipper 52 is mounted to the gasket 5 and a paper-sliding door frame 8 is inserted into the fixing frames 6 and 61 and glass 1 is fixed with a virtually C-shaped gasket 9 in its cross section. In this C-shaped gasket 9, the width dimension of an outer face 91 is made smaller than that of the indoor side, thereby forming a zipper 10 on the indoor side of the gasket 9. This constitution makes it possible to enhance the degree of freedom for appearance design of a window frame and shorten the building construction period.