The experiment was made to study the effect of levels of metabolizable energy of basal diets on apparent metabolizable energy (AME) and true metabolizable energy (TME) values of corn and soybean meals. The test materials, corn and soybean meals, were substituted with basal diet at 50% and 30%, respectively. The excreta of fed md unfed birds were collected for 30 hours. The results obtained were as follows; 1. The AME values of corn were not significantly different among treatments (P＞0.05) except for 2400 Kcal/13% treatment, The AME values of soybean meals differed significantly between 2,400 Kcal/13% and 2,800 Kcal/15% or 3,000 Kcal/16%, but were not different between 2,400 Kcal/13% and 2,600 Kcal/14 % (probability at 5% level). 2. The energy levels of basal diets did not affect the AME values of corn and soybean meals (P＞0.05) except 2,400 Kcal/13% treatment. This fact indicates that it is not necessary to change energy levels of basal diet according to test materials. 3. That the values of standard error of soybean meals were higher than those of corn was resulted from its low level of substitution with basal diet. 4. The TME values of corn showed significant differences (P＜0.05) between 2,400Kcal/13% treatment and other treatments but those of soybean meals were not different among all treatments (P＞0.05). 5. The reason that the AME values of corn and soybean meals and the TME values of corn reduced significantly in 2,400 Kcal/13% could be explained by the effect of interaction among ingredients in the diet.