The purpose of this study was to make a comparative analysis of the music contained in the textbooks of Mongolian yatag and North Korean gayagum. It's specifically meant to discuss the musical influence of Kim Jong-am on the revival of yatag, one of Mongolian traditional instruments. Kim Jong-am was a North Korean gayagum performer and worked as a teacher at a music and dance college in Mongolia from 1961 to 1967. Out of the music included in the Mongolian yatag textbook, 15 pieces of music are liked to North Korean music, which involve Korean folk songs, creative North Korean music, gayagum Sanjo and music composed by Kim Jong-am. Among the 15 pieces of music, the creative North Korean music and Korean folk songs of the Mongolian yatag textbook were compared with those of the North Korean gayagum textbooks published in the 1950s and 1960s. The creative North Korean music of the former was the same as that of latter in terms of musical characteristics, but that's not the case for Korean folk songs. The Korean folk songs of the Mongolian yatag textbook made a repeated use of the varied melodies of the main melodies of Korean folk songs, and included two-part chords from time to time. So the Korean folk songs of the Mongolian yatag textbook sounded more gorgeous and colorful and were consequently characterized by more distinct musical intensity. One noteworthy fact was that although the musical scores of the North Korean gayagum textbooks and Mongolian yatag textbook were the same, there were some differences in the way of unfolding the melody. Kim Jong-am composed yatag music for the sake of his Mongolian disciples such as 'Golden Melody' and 'Children's Dance.' The Korean folk songs he conveyed to his Mongolian pupils were arranged by him, and the originals of Korean folk songs were arranged as well, which served to enrich Mongolian yatag music His Mongolian disciples remembered that he composed yatag music for their sake when he worked as a yatag teacher at a college of music in the 1960s. He had an excellent understanding of the characteristics of traditional Mongolian music and arranged Korean folk songs in a manner to suit the characteristics of Mongolian music. Kim Jong-am was not only a gayagum performer at the 'Moranbong Gamudan' in North Korea but an ethic musician who received modern ethnic music education in North Korea. That was why North Korea sent him to Mongolia when the Ministry of Education, Culture & Science of Mongolia requested North Korea to send a competent person who was capable of providing traditional music education in a modernized manner.