Screen device comprising a screen roller and a screen rollable onto and unreliable from this screen roller and attached on one of its sides to the screen roller, wherein the screen device comprises a frame with at least a protective casing and two lateral guides, wherein the lateral guides each comprise a first profile having a first rail for guiding the screen roller and each comprise two further profiles which, when the two further profiles are connected to said first profile, together form a second rail for guiding the lateral sides of the screen when the screen is rolled up and unrolled.