Strain $CH7^T$, a pale yellow-pigmented bacterium and new isolate from deep subsurface water of the South Coast of Korea, was subjected to a polyphasic taxonomic study. $CH7^T$ grew between 5 and $37^{circ}C$, pH 5.3-10.5, and tolerated up to 13% NaCl. A phylogenetic analysis based on 16S rRNA gene sequences showed that strain $CH7^T$ was associated with the genus Arthrobacter and phylogenetically closely related to the type strains Arthrobacter tumbae (99.4%) and Arthrobacter parietis (99.1%). However, DNA-DNA hybridization experiments revealed 2.1% and 12% between strain $CH7^T$ and Arthrobacter tumbae and Arthrobacter parietis, respectively. Thus, the phenotypic and phylogenetic differences suggested that $CH7^T$ should be placed in the genus Arthrobacter as a novel species, for which the name Arthrobacter subterraneus sp. novo is proposed. In addition, the type strain for the new species is $CH7^T$ ($=KCTC;9997^T=DSM;17585^T$).