A window blind includes a housing, a slat assembly, a slat angle adjusting device, and a first cord. The slat assembly is provided below the housing, and has multiple slats and a bottom end portion. The slat angle adjusting device includes a rotating shaft assembly provided in the housing, and a ladder assembly which includes at least two ladders connected to the rotating shaft assembly for turning the slats. The first cord passes on a front or a rear side of the slats, and connects the rotating shaft assembly and the bottom end portion. Throughout the duration of the rotation of the rotating shaft assembly, the first cord and a warp, which belongs to the ladder assembly and on the same side as the first cord, are both reeled into or out of the housing concurrently, and the slats and the bottom end portion are all rotated concurrently as well.