Korea experienced a financial crisis in 1997. Since then Korea economy has undergone severe change such as exchange rate regime from the market average exchange rate system to the free floating exchange rate system in 1997, and the currency rate fluctuation has been widening. We empirically analyze the determination of the Won/Dollar exchange rate based on the monetary approach. We employ Lucas (1982), Bilson (1978) and Frankel (1979) models and consider some mixed models. We make use of monthly data of money supply, income, interest rate, capital balance, terms of trade, and the yen/dollar exchange rate over the period 1990-2009. We compare the empirical results of cointegration tests and the vector error correction model(VECM) from the two regimes, the pre and post korean financial crisis. The won/dollar exchange rate has long-run relationship with the variables in the monetarist models in the two regimes. For the post crisis regime, the Bilson model is the best and the long run variables also affect the short run dynamics of the won/dollar exchange rate.