The present invention relates to a roller shutter in which a slat connection structure is very flexible so as to reduce manufacturing and maintenance costs. The roller shutter of the present invention comprises: a plurality of slats continuously connected in the vertical direction; a winding unit for winding or unwinding the plurality of slats in the vertical direction; a shutter box arranged above a door frame of a building; and a guide frame for guiding the edges of the plurality of slats. The winding unit is arranged inside the shutter box. The plurality of slats are connected in the vertical direction such that the slats can be pivoted. One end of each slat has a hook, and the hook is curved with a predetermined radius of curvature. The other end of each slat has an accommodation groove curved at a predetermined radius of curvature. The hook of one slat is accommodated in the accommodation groove of another slat adjacent to said slat such that the hook is movable in the circumferential direction, thus enabling said slat and the other slat adjacent thereto in the vertical direction to pivot relative to one another. The hook has an inner surface and an outer surface. The accommodation groove has a first inner surface, a second inner surface, a closed surface, and an opening. The radius of the second inner surface of the accommodation groove is larger than that of the first inner surface. The first inner surface extends in the circumferential direction so as to form a cylinder. The inner surface of the hook and the first inner surface of the accommodation groove have the same radius, and the outer surface of the hook and the second inner surface of the accommodation groove have the same radius.