Folding shutter, comprising - a part (2, 20) which is immovable in the fitted position; - a basic shutter part which is attachable to the immovable part (2, 20) and is rotatable with respect to said immovable part (2, 20) about a fixed rotation shaft; - one or more shutter extension parts which is/are rotatable with respect to the immovable part (2, 20) about a displaceable rotation shaft, in which all said shutter parts are pivotably connected to one another in a concertina-like manner and in which the folding shutter is displaceable between a closed position, in which said shutter parts (3, 4) extend virtually in line with one another, and an open position, in which said shutter parts (3, 4) extend at an angle with respect to one another or parallel to one another as a result of a displacement of the displaceable rotation shaft; - drive means (7, 8, 19, 24) which engage with one of said shutter extension parts for driving the movement of the displaceable rotation shaft; and - locking means (9, 10), comprising first locking means which are attached to the immovable part and second locking means which are attached to one of said shutter parts (3, 4), in which the locking means (9, 10) engage with each other in order to lock the folding shutter in the closed position when the folding shutter is moved to the closed position; characterized in that the folding shutter comprises a actuator rod which is attached to the last-mentioned shutter extension part virtually at right angles to the displaceable rotation shaft, the actuator rod being arranged as to be movable in a bar of this shutter extension part, between a starting position and an end position, said bar being designed as a guide profile, in which the actuator rod can be moved in a guided manner, in which said drive means (7, 8, 19, 24) are connected to said actuator rod in order to drive the movement of the actuator rod, the movement of the actuator rod being driven asynchronously with respect to the movement of the shutter extension part with which the drive means (7, 8, 19, 24) engage, and in which the second locking means are attached to said actuator rod in order to attach said second locking means to the respective shutter part (3, 4), in such a manner that when the folding shutter is moved to the closed position, the locking means (9, 10) engage with each other at the end of said displacement, when the actuator rod is moved from its starting position to its end position. - a part (2, 20) which is immovable in the fitted position; - a basic shutter part which is attachable to the immovable part (2, 20) and is rotatable with respect to said immovable part (2, 20) about a fixed rotation shaft; - one or more shutter extension parts which is/are rotatable with respect to the immovable part (2, 20) about a displaceable rotation shaft, in which all said shutter parts are pivotably connected to one another in a concertina-like manner and in which the folding shutter is displaceable between a closed position, in which said shutter parts (3, 4) extend virtually in line with one another, and an open position, in which said shutter parts (3, 4) extend at an angle with respect to one another or parallel to one another as a result of a displacement of the displaceable rotation shaft; - drive means (7, 8, 19, 24) which engage with one of said shutter extension parts for driving the movement of the displaceable rotation shaft; and - locking means (9, 10), comprising first locking means which are attached to the immovable part and second locking means which are attached to one of said shutter parts (3, 4), in which the locking means (9, 10) engage with each other in order to lock the folding shutter in the closed position when the folding shutter is moved to the closed position;