In this study, 16 female vocational students were targeted to examine the effects of differences in breakfast composition on attentiveness/concentration and mathematical/memory ability. All subjects were asked to eat a balanced meal (well balanced meal in protein, fat, and carbohydrates) and an unbalanced meal (mainly staple food) twice each for a total of 4 days as breakfast, and the change of attentiveness/concentration and mathematical/memory ability for 90 minutes after the meal was compared. For attentiveness/concentration, the correct answer rate and incorrect answer rate were calculated from a visual reaction test using a personal computer. For mathematical/memory ability, the mathematical/memory ability score was calculated using the Kraepelin test. The results of this study suggest that the mathematical/memory ability is higher on the balanced diet intake day than on the unbalanced diet intake day. On the other hand, regarding the attentiveness/concentration, there was no significant difference between the day of eating a balanced diet and the day of eating an unbalanced diet. In order to clarify the effect of the protein-fat-carbohydrate ratio of breakfast on attentiveness/concentration and mathematical/memory ability, it is necessary to add the measurement items, such as the metabolic dynamics in the body and the neural activity of each region of the brain, and to study them in the future. It was suggested that a balanced diet is important for improving mathematical/memory ability.