Using UN Statistics Yearbook 1989-2000, this paper aims at to work out the revealed comparative advantage (RCA) of IT manufactured exports among North Eastern Asian Countries. To achieve the result we, in the first step, calculated each of three countries' eleven information and technology product sectors' indices and ranked with which values are over unity. In the second step, we computed averages of respective each of three countries' RCA indices between the first period (1989-1991) and the second period (1998-2000) to observe the changes in export patterns and comparative advantage. In the third step, we defined four intervals of the RCA index to see if the comparative advantage position of a given sector has improved or worsened between the two periods. We also ranked those sectors recorded a rise of around fifty percent to observe which sectors experienced the strongest shift in the revealed comparative advantage. In the fourth step, we took a glance at whether a country was specialized in IT exports sector or not. Then we figured out their standard deviation and means by setting year 2000 as a basis. Finally we utilized $\emph{Spearman}$'s rank correlation coefficient to see each of three countries' structure adjustment.
Statistical evidence for this period shows that while Korea and Japan have suffered a comparative advantage loss, China has captured the comparative advantage greatly and caught up with them closely. We also recommend that Northeast Asian countries should exert to cooperate together well to build up a united market especially in IT export sectors and reduce taxes on manufactured imports gradually to mitigate the effect caused by the domestic market protection policies.
