This paper discusses the declamation of Mussorgsky's songs. Mussorgsky faithfully duplicated the intonation of Russian language for his music. I selected his 10 songs, and then compared the actual speech with those songs, at the point of those pitch and rhythm. I worked out the percentage which shows how close the song is to its speech, on the result of comparison. Those 10 songs selected from the initial, middle and last period of Mussorgsky's life. Then, I viewed changes in the declamation of Mussorgsky, by my experiment. The results of comparison, the degree of agreement on pitch between the speech and its song was higher and higher in process of time. However, the degree of agreement on rhythm wasn't so. In the middle period, the degree became higher, and in the last period, it became lower. In short, the aspect of Mussorgsky's declamation differs in a pitch and rhythm. Moreover, his declamation has different styles by a form of lyric -a verse or a prose.