This is a report on 40 species of the crabs which were collected during the period from July, 1958 to October , 1959 in the estern sea of Korea (East Sea) belonging to Kyungsang-pukto, apart of Kangwondo and Kyungsang -namdo. Among these, 17 915 genera, 8 families) are unrecorded species in the eastern sea and Platymaja wyville-thomsoni MIERS is an unrecorded species in Korea. Korea (Kuryongpo)seems to be the northern limit of the distribution of this species up to the present. 18 hitherto unreported species are added to the 39 known species, the total in the eastern sea being 57 species involved in 41 genera and 13 families, which show 44.5% of presently known 128 species of crabs in Korea.