To understand the traditional knowledge of botanical taxa in Jeju Island, a diachronic study was carried out by comparing the archaic and modern names of the native plants in Jeju Island. To identify the archaic names of the plants, five old documents (Sejongshillokchiriji, Shinjŭngdonggukyŏjisŭngnam, T'amnaji, Namhwanbangmul and Jejugyerok) that were written during the Joseon Dynasty between the 15 th and 19 th centuries were closely examined. A total of 131 taxa (65 families, 112 genera, 118 species and 13 varieties), 7.3% of the native plants known to be currently present in Jeju Island, was identified. Out of these, 21.4% was the plants found in the southern area. Among the five old documents analyzed for this study, Namhwanbangmul recorded the largest number of plants, 89 taxa. We closely examined the consistency between the modern and archaic names of each plant, and discussed the problems in matching the names of some plants analyzed in this study.