This report describes a new species of the soboliphymid nematode, Soboliphyme ataahai sp. n. from Laxmann's shrew, Sorex caecutiens. This species is distinguished from the previously known congeners by the notched cephalic sucker with a thin circumoral membrane, relatively long vagina, cephalic papillae arranged in clusters, and bursa possessing papillae on inner and outer surfaces. Also, Soboliphyme ataahai differs from the congeners in other characters, such as position of vulva, number and distribution of cervical sacs, structure of cephalic sucker, body size, and dimensions of organs.