This study has been performed to analyze nutrition knowledge, dietary self-efficacy and eating habits of the elementary- and middle- school students (n = 342) according to student's stage of regular breakfast or exercise. Middle school students had higher nutrition knowledge than primary school students. Total dietary self-efficacy and dietary habit scores were not different by school year and gender. Nutrition knowledge, dietary self-efficacy and dietary habit scores were positively correlated each other. By the stage of regular breakfast, the pre-contemplation stage comprised 13.6%, contemplation 2.1%, preparation 15.7%, action 11.5% and maintenance stage 59.1%. By the stage of regular exercise, the pre-contemplation stage comprised 20.9%, contemplation 7.3%, preparation 45.6%, action 9.8% and maintenance stage 16.4%. According to the stage of change, movement from the pre-contemplation and contemplation to upper stage increased the dietary self-efficacy score. Dietary habit score increased significantly across the five stages of changes. The results of this study indicate differences in stages of changes in breakfast intake and regular exercise and indicate the need for taking these phases of change into account in nutrition education.