Recent studies on identity development process have reported that identity achievement occurs after early adulthood. Nevertheless, certain changes in early adolescence can mark the beginning of identity development. Thus, this study examines the state of identity from late childhood to middle adolescence and explores the aspects of self-consciousness related to identity development. The study recruited 2,092 students from the sixth year of elementary school to the third year of high school. States of identity were measured using the Dimensions of Identity Development Scale (DIDS). The mean of the DIDS sub-scores and the proportion of identity statuses for each grade demonstrated that identity awareness increased with the increase in year level during the junior high and high school. Initially, identity awareness decreased to the lowest status during the first year of junior high school. Moreover, DIDS scores were significantly positively correlated with private self-consciousness. In summary, this study found that the process of identity development begins upon entering junior high school and is associated with the stimulation of private self-consciousness.