PURPOSE: To concurrently attain the improvement of a thermal load and dimming near an opening section by overlappingly arranging multiple nontranslucent shielding plates having many through holes at the window opening section, and relatively moving the shielding plates in the plane direction to control the transmitted light quantity passing through the through holes of the shielding plates.

CONSTITUTION: Flexible thin shielding sheets 10, 20 are practically overlapped on the indoor side of a glass forming a translucent opening section 1, e.g. in parallel with the glass, and many small through holes are formed on the sheets 10, 20. When one or both of the sheets 10, 20 are moved in the plane direction and the through holes of them coincide, the solar light S enters a room via the through holes. When the sheets 10, 20 are drifted, only part of the through holes coincide, the light input quantity is reduced, and dimming can be optionally selected. The solar radiation is reflected on the sheets 10, 20, and the heat input to a room is interrupted. When the dimming quantity is adjusted, the incidence quantity of the radiation heat into the room by the solar light S can be adjusted, and the room temperature can be adjusted.