本研究之主要目的在探討國中學生在學習指數律的概念時的主要錯誤類型及造成錯誤的原因，希望藉由此研究結果幫助國中教師們更有效地教學指導學生指數律相關概念。 本研究採紙筆測驗和面談相互配合的方式進行，藉由紙筆測驗調查學生在學習指數律時常犯的錯誤情形，再經過面談的過程進而了解學生的思考方式及運算過程中犯錯的原因。 本研究的實驗對象為新北市兩所公立國中的國三學生共計224名有效樣本，研究者利用自編的「指數律學習測驗」對其施測。經由施測結果，我們利用統計分析彙整出學生計算指數律概念問題時8大常見錯誤類型，以及8個犯錯的主要原因。最後，我們根據此研究的成果提出一些建議及未來研究方向，希望此研究成果能提供國中數學教師作為教學及編製測驗卷的參考。 The main purpose of this study is to explore the error types of junior high school students’ concepts of learning exponential laws and the most possible reasons leading to these errors. We hope this study would be able to help junior high school teachers teach their students these concepts more efficiently. This study adopts paper test accompanying with interview; by writing test, this study investigates the mistakes that students often made when learning exponential laws, then from the process of interview, it reveals students thinking pattern and the causes of the errors during their calculation process. The subjects of this study were 224 students in the ninth grade of two public junior high school from New Taipei City as the effective samples. The instruments applied to this study are “Laws of Exponents Concept Learning Test” made by the author. According to the result of these tests, we statistically analyze the data and draw the conclusion of 8 major error types and 8 primary causes of errors when students learning exponential-law concepts. At last, we provide some suggestions and possible future research directions. Hope this study can be helpful and be able to for the reference of junior high school mathematical teachers when teaching and making up examination papers.