The purpose of this essay is to clarify the modulation technique used in Chunhyang-ga(Song of Chunhyang) of Manjeong (Kim So-hui) style. For this purpose, the jinyangjo parts that the modulation technique is most used are examined. Examining the three pieces, Jeogeonneo(Over there), Yieukgo(At last), Sarang-ga(Song of Love), the research has revealed the following conclusions. The modulation techniques used in the three pieces have the relationship of closely related keys and relative keys. The modulation techniques mostly used are the following three; to use the middle key of the preceding part as the under key of the following part, to use the same tone or the octave higher, and to use the passing phrases. Among the techniques of using the passing phrases, the modulation key of the preceding part is used without any exceptions when ujo-gil moves to gyemyeon-gil. The parts that the modulation are most frequently used are the middle part of Jeogeonneo, the latter part of Yieukgo and after one-third point of Sarang-ga. They use various modulation techniques alternately rather than using the same types repeatedly. This essay belongs to the first step of the study of the modulation techniques used in the songs sung by Manjeong, Kim so-hui. All the parts of Chunhyang-ga sung by Manjeong will be examined step by step. The study of these various modulation techniques will help understand the Chunhyang-ga sung by Manjeong. It will also be helpful to making different styles of singing and to composition.