Closure device of the type roller shutter, mosquito net, blind, garage door or the like for equipping an opening defined at the level of a building, and comprising: - an element for shading said opening and including at least one slat (20; 22; 24) including a first slat portion (20; 22; 24) and a second slat portion (20; 22; 24) movable relative to each other; - side guides (4; 4') inside which the side ends (26; 26') of at least one slat (20; 22; 24) of the shading element move; - at least one system for impeding the shading element from being lifted, and including: - a hooking organ forming a keeper, and which the second slat portion (20; 22; 24) is provided with; - at least one latch pivotally mounted between a locking position, in which this latch cooperates with the hooking organ for impeding the lifting, and an unlocked position, in which this latch is retracted with respect to the hooking organ; - a means for pushing the latch from a locking position into an unlocking position under the action of a displacement of the slat (20; 22; 24), wherein: - the latch said at least one system includes for impeding the lifting and which at least one of said side guides (4; 4') includes internally is pivotally mounted on an inner wall (40; 40a) of such a side guide (4; 4'); - the first slat portion (20; 22; 24) is provided with the means for pushing the latch into an unlocked position; - the means for pushing the latch is formed of a cam track extending towards the second slat portion (20; 22; 24) and/or along this second slat portion (20; 22; 24). - an element for shading said opening and including at least one slat (20; 22; 24) including a first slat portion (20; 22; 24) and a second slat portion (20; 22; 24) movable relative to each other; - side guides (4; 4') inside which the side ends (26; 26') of at least one slat (20; 22; 24) of the shading element move; - at least one system for impeding the shading element from being lifted, and including: - a hooking organ forming a keeper, and which the second slat portion (20; 22; 24) is provided with; - at least one latch pivotally mounted between a locking position, in which this latch cooperates with the hooking organ for impeding the lifting, and an unlocked position, in which this latch is retracted with respect to the hooking organ; - a means for pushing the latch from a locking position into an unlocking position under the action of a displacement of the slat (20; 22; 24), wherein: - a hooking organ forming a keeper, and which the second slat portion (20; 22; 24) is provided with; - at least one latch pivotally mounted between a locking position, in which this latch cooperates with the hooking organ for impeding the lifting, and an unlocked position, in which this latch is retracted with respect to the hooking organ; - a means for pushing the latch from a locking position into an unlocking position under the action of a displacement of the slat (20; 22; 24), - the latch said at least one system includes for impeding the lifting and which at least one of said side guides (4; 4') includes internally is pivotally mounted on an inner wall (40; 40a) of such a side guide (4; 4'); - the first slat portion (20; 22; 24) is provided with the means for pushing the latch into an unlocked position; - the means for pushing the latch is formed of a cam track extending towards the second slat portion (20; 22; 24) and/or along this second slat portion (20; 22; 24).