To inspect, confirm and adjust the arranging state of an article or an air pad by providing at least one opening and closing window to the side surface of a folding container equipped with a lid transported by fixing content by an air pad.

A folding container main body 1 consists of a frame 2, long side panels 3, short side panels 4 and a bottom panel and each of the long side panels 3 is formed by connecting upper and lower side panels 31, 32 by a hinge part 33 and at least an opening and closing window 6 is provided to the side surface of the container. The thin-walled part of the opening and closing window 6 becomes a hinge mechanism to forwardly bend the window 6 and the inverted U-shaped engaging piece formed to the upper end of the opening and closing window 6 is engaged with the projection formed to the upper end of the opening part of the window 6 when the window 6 is closed. By this constitution, the content in the container is fixed by an air pad and, when the container is transported after a lid is applied to the container, the inspection of a packed article is performed through the opening and closing window 6 and the fixed state by the air pad is adjusted.