The purpose of this study is to grasp the folk song recognition around the 1920`s with newspapers and magazines as the objects and to examine the folk song theory of Uidongin serialized in ``Jungwoeilbo`` in the 1920`s. Before the 1920`s folk song words were printed with the name of ``Children``s Song`` on newspapers and magazines or only the words were printed. Then children`s song did not mean ``Song of Children``, that was classified into lower rank of folk song, but meant ``The Mind of Heaven``. Before Uidongin Lee Kwang-Soo, Yang Myeong, Yeom Sang-Seob, Park Buk-Hyang, and Hong Sa-Yong made efforts to define ``Folk Song``. First of all, Uidongin defined folk song as ``Song of the Race, Song of the People and Song of the Nation``. In that period, Joseon was dominated by the Imperial Japan first in her history and a national system was introduced. And the concepts of ``race`` ``people`` and ``nation`` were not internalized in the thought of an intellectual as modern system but were in a confusion. And he wrote that folk songs did not embellish at all, were sung with naivety and innocence, and made simple genuine sensation without impure utilitarian elements revealed, touching popular psychology. Here the words of "naivety" "innocence" and "genuine sensation" are related with the unartificialIdleness(無爲) used in ``Jangja(莊子)`` among oriental aesthetics. Uidongin wrote that folk songs express candid mind without embellishment and this is due to the Oriental view of the folk song. And he explained the merits of folk songs as follows. First, the author of folk songs are unknown. Second, folk songs are floating literature. Third, folk songs are with melody. Fourth, in folk songs the special products, custom, and life of the region are represented. Fifth, folk songs are easy to sing. Second, Uidongin looked upon the transition of folk songs as circulation and wrote that the author became obscure and the meaning changed as folk songs were transmitted. He explained the circulation in time and space. First, time circulation may weaken once but may revive with a chance afterwards. There is a change in the form that are melody and words. Next, in spatial circulation, the melody and words change with circulation from one region to another. Namely, time circulation means the transmission of folk songs and the spatial transmission means the spreading of folk songs. And the factors of folk song development are explained in six. First, what were extinct in the native place, when the Gyeongbokgung Palace wasrebuilt, partly remained in Gyeongseong. Second, the encouragement of folk songs by Emperor Gojong gave birth to the new folk songs(新民謠). Third, the role of the demimonde who learnt folk songs was great. Fourth, the number of those who studied folk songs increased. Fifth, estranged celebrated singers emerged. Sixth, magazine publishers collected folk songs. Lastly, Uidongin classified folk songs into two kinds, centering on the expression. First, in the expression form, they were classified into vulgar songs, popular songs, children`s songs and created folk songs. Next, in the principal and auxiliary relation by the expression subject, they were classified into narrative folk songs and lyric folk songs. This seems to be influenced by Tanaka(田中初夫) of Japan.