To cope with two kinds of paper with charged polarity opposite to each other with simple structure for practical use.

A paper dust eliminator has means 31a-31c for applying an acid base indicator to part of sheets of paper 11a-11c stored in paper feeders 12a-12c for feeding paper to a carrier roller 17, means 32a-32c for reading reaction colors of the sheets of the paper 11a-11c at the time of application, and a means 23 for automatically judging the kinds of paper 11a-11c from the reaction colors and automatically switching the polarity of electric charge applied to a carrier roller 17. Paper dust is captured and eliminated by the impression of voltage of polarity corresponding to the kinds of the sheets of the paper 11a-11c.