本文以事件研究法，討論美國食品暨藥物管理局在核准新藥上市的宣告效果。結果顯示在宣告日當天，各藥廠的異常報酬沒有顯著改變，但在宣告日的前五十天交易日可以觀察到顯著的累計異常報酬，根據美國食品暨藥物管理局的審核新藥流程以及學術性期刊對於新藥的臨床實驗數據探討，亦或是新聞對於新藥療效的提前揭露，推測皆會影響事件日之前的股價反應。進一步根據會計資料的觀察，新藥的核准上市，對於藥廠的營收雖沒有顯著改變，仍可以看出有增加的趨勢。最後，諸多新聞指出分析師對於新藥的審核過程中可以取得此藥物是否會通過美國食品暨藥物管理局的內線消息，結果顯示約有41％的分析師可以準確預測藥物是否可以通過，或許跟製藥業不同於其他產業的流程導致內線消息流出有關。 / In this paper, we use event-study to estimate the stock price changes of Food and Drug Administration (FDA) decisions on new products for pharmaceutical companies. We find that FDA decisions have insignificant effects in all countries on the drug approval date. The insignificant price changes accompanying FDA announcements approval suggest that drug results have leaked to the market. It is quite possible that the results of advisory are open to public and advisory committee are held before FDA approval, advisory committee can be viewed as important news source of drug approval. After the drug approved by the FDA, the new drugs may bring additional income to the companies. Although the accounting data are insignificant at five percent significant level, we still can peek that the companies with new approval drug have their EPS increase. Besides, 41% of analyst rates the performance of next quarter better than actual EPS at that time. The reason can be the access of undisclosed information about successful approval of new drugs.