A Gram-negative, non-motile, non-spore-forming, small, orange, rod-shaped bacterium was isolated from soil in South Korea and characterized to determine its taxonomic position. Phylogenetic analysis based on 16S rRNA gene sequence examination revealed that strain PB323$^T$ belongs to the family Sphingomonadaceae. The highest degree of sequence similarity was found with Sphingomonas kaistensis PB56$^T$ (98.9%), followed by Sphingomonas astaxanthinifaciens TDMA-17$^T$ (98.3%). Chemotaxonomic characteristics (the G+C content of the genomic DNA 69.0 mol%, Q-10 quinone system, $C_{18:1}{omega}7c/{omega}9t/{omega}12t$, $C_{16:1}{omega}7c/C_{15:0}$ iso 2OH, $C_{17:1}{omega}6c$, and $C_{16:0}$ as the major fatty acids) corroborated assignment of strain PB323$^T$ to the genus Sphingomonas. Results of physiological and biochemical tests clearly demonstrate that strain PB323$^T$ represents a distinct species and support its affiliation with the genus Sphingomonas. Based on these data, PB323$^T$ (=KCTC 12341$^T$ =JCM 16603$^T$ =KEMB 9004-003$^T$) should be classified as a type strain of a novel species, for which the name Sphingomonas humi sp. nov. is proposed.