To attain daylighting in part even if inclining slats and moreover to facilitate operation with a simple structure.

Each of a plurality of slats 2 mounted to ladder cords 1 is composed of a light transmitting part 2A and a light shading part 2B formed along the longitudinal direction. The light transmitting parts 2A of the vertically adjoining slats 2 are arranged alternately from the side face view, and two different slat spaces d1, d2 are provided so that the light transmitting parts 2A of the adjoining slats 2 overlap each other when inclining the slats 2 in one direction.