To suppress decline in the quality of an object to be weighed in a weighing process in a combination weigher as much as possible and perform a high dust-proof function.

A sealing cover 20 covers the surroundings of a combination weigher 2, and nitrogen gas is filled in the sealing cover 20. The sealing cover 20 includes a housing frame 25 for surrounding the combination weigher 2, cover plates 26 for closing openings provided to the housing frame 25, and magnetic attraction means for fixing the cover plates 26 to the housing frame 25 in a removable manner.