This study aims to examine if changes of exchange rates of won/dollar, of won/euro and of won/yen from 1994 to 2005 mean structural changes and to test them as normal time series. We have tested frequency of the structural changes by means of Bai-Perron test, and carried out aunit root test by Zivot-Andrews method and Perron method. In result, two statistical significances have been confirmed. First, the exchange rates of won/dollar and won/yen have gone through a structural change in constant number term, and we could judge them to be normal time series, considering the structural change. Second, a structural change has not occurred to the case of won/euro, which could be judged to be abnormal time series, being irrelevant to the structural change. These results mean that the drastic fluctuation of the exchange rates of won/dollar and won/yen could be considered as structural and stable change in the last 10 years change structure. However, we found that the change structure of the exchange rates of won/euro after 2000 was not quite different from that of the period of foreign exchange crisis. Accordingly, we infer that the fluctuations in the period of foreign exchange crisis could not be considered as structural change and that they prove overall their unstable tendency. This empirical study concludes that this phenomenon results from a structural unstability of the euro currency, a continuing evaluation tendency after 2002 and a strong connection of the exchange rates of won/euro to those of won/dollar.