The foreign exchange market and the stock market are both important for the open economy's development, and Taiwan's electronic industry is prosperous. This Thesis is to discuss the causal relation between Taiwan Electronic Sector Stock Index and the exchange rates of NT dollar to US dollar and to Japanese yen. In order to find the effects of real exchange rate and nominal exchange rate respectively, the nominal data are daily and real data are monthly. The empirical results show: when NT dollar depreciates toward dollar, the index of Taiwan Electronic Sector will rise in the same day. Moreover, the effect can retain for three days and five days which means there is no over shooting. But the volatility of nominal exchange rate between NT dollar and yen doesn't lead any significant effect. The volatility of real exchange rate between NT dollar and yen, the monthly data, can affect the return rate of Electronic Sector Stock Index, and the direction is negative. But the volatility of nominal exchange rate between NT dollar and dollar doesn't lead any significant effect.