To catch no garbage of a string-like shape in a screw by providing a throwing port and a discharge port at a front side of a storage chamber and to deviate no storage amount of the garbage by the screw of a constant rotation direction.

The condition for switching to normal/reverse rotation is solved by making one screw by an impeller and a shaft in a screw type dust storage machine. Firstly, a means for throwing the garbage without deviating to a rearward direction can be provided by making a rear end of a shaft of the screw to a free end part. Secondly, a means for discharging the garbage without catching the garbage of the string-like shape can be constituted by making a front end of the shaft to a cantilever part, providing a bearing on a front wall of an advancement/retreating bucket and penetrating and pivotally mounting the front end of the shaft to the bearing.