A screen device comprising: a pair of screen mounting frames (1a, 1b) disposed opposite to each other, at least one of which is slidable; a screen mounted between said screen mounting frames (1a, 1b) so as to be capable of being opened and closed; a pair of sliding guide frames (10a, 10b) each of which is disposed near one of the sides of said screen which are not mounted to said screen mounting frames (1a, 1b), at least one end of which is a free end which is capable of being received in and withdrawn from inside of one of said screen mounting frames (1 a, 1 b); wherein said sliding guide frame (10a, 10b) is formed of a plurality of interconnected rigid units each of which has a pair of sidewalls disposed opposite to each other and a bridging portion interconnecting said sidewalls, and adjacent rigid units are rotatable relative to each other, whereby the sliding guide frame (10a, 10b) is bendable and the sliding guide frame (10a, 10b) preserving straightness of a withdrawn portion of the sliding guide frame (10a, 10b) when the sliding guide frame (10a, 10b) is withdrawn from the screen mounting frame (1a, 1b) in accordance with sliding movement of the screen mounting frame (1 a, 1 b); characterized by a pair of vertical rails disposed opposite to each other, putting the screen between said vertical rails, and connected to each other; a connecting member for connecting said vertical rails, said connecting member having a spacer, one of the sides of which is attached to the screen; a tensioning member extended between the pair of screen mounting frames (1a, 1b); wherein said connected vertical rails are fixed to the sliding guide frames (10a, 10b) and are capable of sliding parallel to a sliding direction of the screen mounting frame (1 a, 1 b), a clearance with a width corresponding to the thickness of said spacer is formed between the screen and one of the vertical rails, and the tensioning member passes through said clearance. a pair of screen mounting frames (1a, 1b) disposed opposite to each other, at least one of which is slidable; a screen mounted between said screen mounting frames (1a, 1b) so as to be capable of being opened and closed; a pair of sliding guide frames (10a, 10b) each of which is disposed near one of the sides of said screen which are not mounted to said screen mounting frames (1a, 1b), at least one end of which is a free end which is capable of being received in and withdrawn from inside of one of said screen mounting frames (1 a, 1 b); wherein said sliding guide frame (10a, 10b) is formed of a plurality of interconnected rigid units each of which has a pair of sidewalls disposed opposite to each other and a bridging portion interconnecting said sidewalls, and adjacent rigid units are rotatable relative to each other, whereby the sliding guide frame (10a, 10b) is bendable and the sliding guide frame (10a, 10b) preserving straightness of a withdrawn portion of the sliding guide frame (10a, 10b) when the sliding guide frame (10a, 10b) is withdrawn from the screen mounting frame (1a, 1b) in accordance with sliding movement of the screen mounting frame (1 a, 1 b); characterized by a pair of vertical rails disposed opposite to each other, putting the screen between said vertical rails, and connected to each other; a connecting member for connecting said vertical rails, said connecting member having a spacer, one of the sides of which is attached to the screen; a tensioning member extended between the pair of screen mounting frames (1a, 1b); wherein said connected vertical rails are fixed to the sliding guide frames (10a, 10b) and are capable of sliding parallel to a sliding direction of the screen mounting frame (1 a, 1 b), a clearance with a width corresponding to the thickness of said spacer is formed between the screen and one of the vertical rails, and the tensioning member passes through said clearance.