Pseudisobrachium is one of the biggest genera with 190 species from the world including one extinct species from France. In Korea, only one species, P. koreana Lim, has been recorded. The ecological information of Pseudisobrachium is poorly studied, however, it was recorded that Pseudisobrachium species are found associated with various ants in several previous studies. As results of taxonomy studies on the Korean bethylids, a new species of Pseudisobrachium is discovered based on one female specimen which was collected from Cheongsong county (Gyeongbuk province) by Malaise trap in 2008. This is the first record of female of the genus in Korea. A taxonomic discussion on the genus Pseudisobrachium, diagnosis and diagnostic characteristics of the new species are provided.