The Joseon of King Jun (the second Joseon, Jungjoseon) was located in the land of Gojoseon (the first Joseon) that The first Dangun had founded. Wiman wrested the territory from King Jun and became the king of Joseon (the third Joseon, Hujoseon). Wuti of the Han dynasty destroyed the country and established the Lelang Commandery on its territory. Accordingly, the location of Joseon could be found by findingout that of Lelang Commandery. The only one historical record about the location remains in the Yuju Section of the County duchy Records(郡國志), a supplement of the Book of the Later Han(後漢書). It says that the Lelang Commandery was located 5,000ri(2,015㎞) away from Luoyang to the northeast. However, no scholar has ascertained the location of the Lelang Commandery, Gojoseon, Jungjoseon, and Hujoseon in reference to this historic record.This study seeks to ascertain the Qing dynasty’s road routes from Luoyang, Beijing, Shenyang, to Dandong recorded in Daecheongiltongji(大淸一統志) in reference to Aseadongbuyeojido compiled in 1875, compare the length of the road from Luoyang to Dandong in the Qing dynasty with that of the present day road by using a mathematical location measurement method, and find out the actual location of the Lelang Commandery.Assuming that the roads in the Han dynasty were just as flat and linear as those in the Qing dynasty, the result of this study has revealed that the Lelang Commandery was located 22.36㎞ away from Liaoyang City, Liaoning Province to the south. However, as it is thought that the roads in the Han dynastywere less flat and linear that those in the Qing dynasty, it is presumed that the Lelang Commandery was actually located farther than 22.36㎞ away from Liaoyang City, Liaoning Province to the south.