A novel heterotrophic, yellow pigmented, aerobic, Gram-negative, nonmotile, oxidase- and catalase-positive bacterium KMM 3938T was isolated from sea water collected in the Sea of Japan, Russia. The strain grew at mesophilic temperature range, and required the presence of NaCl for growth. 16S rRNA gene sequence analysis revealed that strain KMM 3938T is a member of the family Flavobacteriaceae. The predominant fatty acids were C13:0 iso, C14:0 iso, C15:0 iso, C15:0, C15:1Δ6, 3OH-C15:0:3 iso, and 3OH-C15:0. The G + C content of the DNA of KMM 3938T was 32.4 mol%. On the basis of phenotypic, chemotaxonomic, genotypic, and phylogenetic characteristics, the novel bacterium was assigned to the genus Polaribacter as Polaribacter butkevichii sp. nov. The type strain is KMM 3938T (= KCTC 12100T = CCUG 48005T).