To provide a dustproof cover which effectively prevents scattering of dust when cement from a flexible container containing the cement is charged into a mixer, etc.

The dustproof cover includes a cylindrical trunk which is put over a baglike flexible container containing powdered cement, etc., and a lid plate which covers the upper end of the trunk. At the center of the lid plate, a through-hole is provided to put a hanging string attached to the flexible container through the through-hole, the periphery of which has an upward projecting collar. Pulling and tightening the string disposed around the collar enable the squeeze of an opening.