近來之文獻皆提出會計穩健性（accounting conservatism）能夠緩解代理人與主理人間之資訊不對稱，亦可以促進投資效率（investment efficiency）之提升。基於此，故本研究旨在探討會計穩健性與投資效率對於企業研發投資績效之影響，並以Khan and Watts (2009) 應用Basu (1997) 模型建構之C_Score衡量會計穩健性；以Biddle et al. (2009) 建立之實際投資與預期投資的偏離程度衡量投資效率。 實證結果發現：(1) 企業研發投入強度對於經營績效將會產生遞延效益；(2) 相較於會計穩健性低之企業，會計穩健性愈高之企業研發投資績效愈好。此外，企業之會計穩健性高低分類可能每年皆不同，額外測試之結果發現每年皆分類為高會計穩健組之企業研發投資績效將更好；(3) 相較於投資無效率之企業，投資效率愈好之企業研發投資績效愈好；(4) 相較於會計穩健性低且投資無效率之企業，會計穩健性高且投資效率愈好之企業研發投資績效愈好。 本研究提供有關會計穩健性、投資效率與研發投資績效關聯之證據，亦可以建議未來欲從事研發投資績效之研究應將會計穩健性與投資效率納入考量。;Based on literature, accounting conservatism can reduce information asymmetry between principals and agents and can also improve investment efficiency. Thus, this study aims to investigate how accounting conservatism and investment efficiency influence a firm’s R&D investments that in turn affect its operating performance. This study measures accounting conservatism by using C_Score which Khan and Watts (2009) developed on the basis of Basu (1997) asymmetric timeliness of earnings model. As for investment efficiency, this study uses the residuals as a proxy for deviations from expected investment developed by Biddle et al. (2009) to measure investment efficiency. The results of this study are as follows. First, this study suggests that a firm’s R&D investments have positive and lagged effects on its operating performance. Second, this study suggests that accounting conservatism is significantly positively related to operating performance resulted from R&D investments relative to firms with less conservative financial reporting. Note particularly, this study finds that R&D investments can contribute more for operating performance when firms adopt more conservative accounting principle every year. Third, this study also suggests that compared to firms with inefficient investments, investment efficiency is significantly positively related to operating performance resulted from R&D investments. Finally, this study suggests that compared to firms with less conservative financial reporting and inefficient investments, R&D investments can create more benefits for firms with more conservative financial reporting and efficient investments. This study provides some evidences on the positive relationship between accounting conservatism, investment efficiency and operating performance resulted from R&D investments. The evidences also imply that accounting conservatism and investment efficiency should be considered in future studies analyzing operating performance of R&D investments.