A movable lid 2 provided with a suction hole 13 is mounted on a valve body 1 provided with a venting hole 4 communicating with the inside of the housing bag, the movable lid 2 moving freely both upward and downward. In a normal state, the venting valve is closed with a valve plate 6 kept pressed by a spring 7 in the valve body 1. When the suction nozzle of the vacuum cleaner is pressed against the movable lid 2 and moves it downward, the downward pressure of the movable lid overcomes the force of the spring 7 to open the valve plate 6, then the housing bag is deaerated. After the deaeration has been completed, the suction nozzle is removed from the movable lid 2, which causes the movable lid 2 to return upward to the original position due to the stability of the spring 7, thus the venting valve is closed. Thus, the housing bag can be opened by only pressing the suction nozzle of a vacuum cleaner against the venting valve to deaerate the housing bag, so that the motor of the vacuum cleaner is almost free from load during deaeration, and which can be automatically closed upon releasing the press by the suction nozzle. |