Printers and copy machines produce various types of operation sounds when we open and close front covers, draw and load paper trays, and lock and release their hooks. These sounds contribute to impressions of product quality. In this study, to clarify the features of various operation sounds emitted from laser printers and copy machines, free description experiments using onomatopoeia were examined. As a result of these experiments, we classified sounds according to their onomatopoeic features. Furthermore, to clarify the relationship between product image and onomatopoeic features, the rating experiments on auditory pleasantness and product image such as exclusiveness and robustness were also examined.<br>The vowel /i/ or its prolonged sounds in representations of "sharp" rubbing sounds and voiced consonants in representations of "harsh" striking sounds imply auditory unpleasantness. The vowel /o/ in representations of striking sounds are associated with images of mechanical robustness. This study demonstrates the usefulness of onomatopoeic representation for the evaluation of sound quality related to machinery noise.