A taxonomic study of the intertidal Thinobius Kiesenwetter in Korea is presented. Three species are recognized, two of which are identified as new species (Thinobius jejuensis Lee Ahn, sp. n. and Thinobius koreanus Lee Yoo, sp. n.) and Thinobius kuroshio (Sawada) is recorded for the first time in Korea. A key, descriptions, habitus photographs, and line drawings of diagnostic characters of these three species are provided to facilitate identification.