Arthrobacter spp. are coryneform bacteria known as a soil flora and also part of normal flora of human. Since coryneform bacteria are often reported to be a cause of life-threatening diseases, and especially the human infections of Arthrobacter spp. are reported recently, it is important to identify them to the genus and species levels by additional studies including molecular tests. We report a case of bacteremia caused by Arthrobacter woluwensis, which was misidentified initially as Leifsonia aquatica by commercial kits and conventional tests, but correctly identified by 16S rRNA sequencing.