The sweet potato reached the Korean Peninsula from Tsushima island, in Japan, in 1763 and 1764, through Jo Eom, who led a Korean Embassy to Japan in the late Joseon period. In the Korean government text Seungjeongwon Ilgi it is written that in 1765 Yun Shi-dong, the Governor of Jeju Island, brought a sweet potato seed to Jeju island with the assistance of Gang Pil-lee, who was the Magistrate of Dongnae County, in Gyeongsang Province. And it was recorded in the Seungjeongwon Ilgi that Yun Shi-dong planted the sweet potato seed which had been sent by Jo Eom in 1767. From these documents, it can be confirmed that the sweet potato entered Jeju Island between 1765 and 1767. Jo Eom wrote in his diary that he met Korean drifters at Tsushima island in the sixth lunar month of 1764. They had been carried to Japan from Jeju two months earlier. According to Tsushima domain records of an investigation conducted on the fifth day of the fourth lunar month, Jeju drifters had been rescued by residents of Tsushima on the second day of the fourth lunar month, that is, three days earlier. The Jeju drifters included seven males and four females including one pregnant woman. The eleven Jeju drifters all returned to Joseon safely after the sixth lunar month of 1764. It is suggested in this paper that more attention should be paid to the experiences of the Jeju drifters who met Jo Eom in Tsushima in 1764, one or three years before the arrival of the sweet potato in Jeju between 1765 and 1767. It is clear that this problem will be solved by additional surveys on the early history of the sweet potato in the Korean peninsula.