The invention relates to a folding door and a shutter guide device. The inventive door comprises two vertical slides (2) and at least one flexible shutter (4) which can be folded in the upper part of the slides and which comprises at least one transverse stiffening bar (12). According to the invention, a guide device (14) is inserted into the extension of at least one stiffening bar (12), thereby forming a guide for the shutter (4) in at least one of the slides (2) in a plane that is offset in relation to the plane of the shutter (4), said shutter (4) being applied against a surface of the slide (2).