Although Japan is a small country with 38 million ha of land, most of the lands (67%) are covered by forests. In Hokkaido, the northern most island, main forest types are cool-temperate mixed forests and sub-boreal conifer forests. In these forests, partial harvesting (single-tree selection) has been a common management practice since the early 20th century. However, actual harvesting practices were often excessive and showed preferential extraction of large trees. Partial cuttings also reduce density of fallen logs. All of these factors resulted in degrading of managed forests. We examined the effects of partial harvesting on arthropod diversity. We collected saproxylic beetles in 7 pairs of primary and nearby harvested stands using collision traps attached to snags and Malaise traps. For longicorn beetles, species richness, abundance, and species composition did not differ significantly between primary and harvested stands. Species composition was significantly correlated with several stand variables (elevation, stem density and % conifer volume). Analyses in species level showed that some species were significantly more abundant in primary stands than in harvested stands. These species may be sensitive to harvesting practices.