This study deals with the direction of change of nominalizers `-m` and `-ki` with respect to the preservation, the expansion, and the reduction in the scope of their realizations. The contents discussed here can be summarized as the following. First, in the 19th-century Korean, the scope of nominalization had been expanded in the case that a `-m`-adjoined clause functioned as a subject in a clause and that a `-ki`-adjoined clause functioned as an object. In the 20th-century Korean, the scope of `-m` had been expanded when its realization functioned as an object, and the one of `-ki` was expanded when its realization functioned as a subject. Secondly, `-m` was more frequently used than `-ki` when `-m` and `-ki` each maintained its scope. Thirdly, the mixed uses of `-m` and `-ki` in the same sentence were identical in the two periods. Particularly, the historical evidences of these mixed uses provide the explanation about the direction of change in `-m` and `-ki`.