The purpose of this study is to explore the relationship between national identity, achievement motivation, bicultural acceptance attitude, and achievement motivation of multicultural adolescents focused on developmental change by finding longitudinal effects of national identity and bicultural acceptance attitude on achievement motivation, This study utilized data from the 4th one (1st grade in middle school) in 2014 to the 9th one (3rd grade in high school) in 2019 among the multicultural adolescents panel surveyed by the Korea Adolescents Policy Institute. The analysis cases was 1,072 people who responded to all surveys during the period. Data analysis was performed using SPSS Statistics 25 and Mplus8, and the latent growth model was applied. The analysis results are as follows. First, the higher the initial value(in 1st grade of middle school) of national identity of multicultural adolescents, the achievement motivation increases. Second, the initial value(in 1st grade of middle school) of national identity did not affect on the rate of change in achievement motivation. Third, the higher the rate of change of national identity as age increase, achievement motivation become higher. Fourth, the rate of change in achievement motivation of male student becomes higher than that of female students as age increases. Fifth, the higher the initial value(in 1st grade of middle school) of the bicultural acceptance attitude of multicultural adolescents has positive effects on the achievement motivation increases. Sixth, the initial value(in 1st grade of middle school) of the bicultural acceptance attitude of multicultural adolescents doesn’t have no effects on he rate of change in achievement motivation, Seventh, as the rate of change in the bicultural acceptance attitude of multicultural adolescents increases, the rate of change in achievement motivation also become higher. The rate of change is more important that the initial value in national identity and in the bicultural acceptance attitude in increasing achievement motivation of multicultural adolescents. This result shows active support is needed to promote steady development of national identity and bicultural acceptance attitude of multicultural adolescents. And we need to pay attention to prevent the decline in the rate of increase in achievement motivation among female students compared to male students growing into late adolescence.