Analyzing the samples of silage obtained from dairyfarms in different districts of Japan and from the laboratory, the author investigated into factors that determine the quality of silage; and the results obtained on the quality of silage in various positions in a silo, the change of quality after the removal of silage from a silo, the relationship between the pH value and the ammoniac nitrogen content, and also the result of appraisal of silage by means of FLIEG'S method are described in this paper. The results are summarized as follows: (1) It is rarely possible to state that the quality of silage is always homogeneous throughout in a silo from the upper to the bottom layers, not to speak of the surface spoilage. On the average, the pH value of silage in the middle portion is lower than that in the outer, although it cannot be stated that the difference is always significant. (2) In winter season, the change of quality of silage is rather little within about a week after the removal of silage from a silo, if the silage is preserved without exposure to air. It is suggested therefore that an amount of silage for a few days use may be removed at a time for the purpose of labor-saving. (3) A significant positive correlation, γ=+0.603, was found between the pH value and the ammonia nitrogen content (p<0.001). (4) Examples of the results of the appraisal by means of FLIEG's method are presented in Table 9. A significant positive correlation has been found between the results of appraisals by means of FLIEG'S method and those obtained by GNEIST'S. When the two series of results of evaluation were different, the values obtained by FLIEG'S method were slightly higher than those by GNEIST'S.