The occurrence of major pest infestation was compared between conventional tea plantation and organic tea plantation at Sulloc tea garden in Dosun-dong, Seogwipo-si, Jeju-do from 2002 to 2009. Tetranychus kanzawai was observed a lot in the second year, but it waned from late June. There was not much difference between conventional farming and organic farming in terms of pest density. Empoasca onukii was infested in the second year of organic farming compared with conventional farming, which highlighted the fact that second year of organic farming requires a special care. Scirotothrips dorsalis was highly dense in the second and third year of conventional farming, but its occurrence was lowered when the farming technique was shifted to organic farming. The number of Homona magnanima peaked 4 times each year. In 2008, the first year of organic farming, saw high occurrence of 771.2 per trap per year. In 2009, the second year, the population per trap dropped to 80, showing a great variance depending on year. The occurrence of Caloptilia theivora peaked 5 times annually. In 2008, the first year of organic farming, an average of 2,779 pests per trap was found, and in the following year, 4,143 pests were observed. It showed that density rose in organic growing period.