The invention relates to a valve structure for a sack or the like to be filled with air, which valve structure comprises an essentially cylindrical tubular part (2) extending hermetically from the inside to the outside of the sack and having external threads (21) on the portion outside the sack, a plug with internal threads (13) to be screwed on the external threads (21) of the tubular part (2) to close the end (24) of the tubular part hermetically, and a filling valve (15) in the middle of the plug (1). To facilitate and accelerate the emptying of the sack, the present invention is characterized in that the plug (1) has several air exhaust holes (14) within the area surrounding the filling valve (15), and that at the end of the tubular part (2) facing the plug (1) there is an inner, preferably annular flange part (23), the upper surface of which is pressed hermetically against the lower surface of the plug closing the exhaust holes (14) of the plug, when the plug (1) is entirely screwed in its place.