As a result of continuous taxonomic studies on the Korean crabs, two varunid crabs, Hemigrapsus takanoi Asakura and Watanabe, 2005 and Sestrostoma toriumii (Takeda, 1974), are newly reported from Korean waters. Hemigrapsus takanoi, as a sibling species of H. penicillatus, has not been recognized in Korean waters, and this species occurs in the sympatric habitat with H. penicillatus in the Korean peninsula. Sestrostoma toriumii (Takeda, 1974) is associated with thallassinid Upogebia major (De Haan, 1841) and echiuran Urechis unicintus (Von Drache, 1881) as the case of S. balssi (Shen, 1932). The Korean S. toriumii showed smaller size than those mentioned in the original description. Their illustrations and pictures are provided with descriptions, and the distributions of these species in the Korean peninsula are also provided.