This study was carried out to investigate the non-indigenous of Dokdo belong to Ulleung-gun, Gyeongangbuk-do, Korea, from 2008 to 2011. We divided the study into three steps depending on the recorded times of plants on Dokdo since 1973, when the ecosystem was disturbed by many plantation events. The results are as follows: 30 taxa (52.6%) until 1973, 24 taxa (42.1%) after 1973, and 3 taxa (5.3%) of cultivated plants depending on the 57 taxa of Dokdo. Management of the non-indigenous plants of Dokdo is necessary due to the great increase in interest by people, with many visitors to Dokdo.