本研究旨在探討沙氏法302條款（Sarbanes-Oxley Act Section 302，以下簡稱SOX302）、沙氏法404條款（Sarbanes-Oxley Act Section 404，以下簡稱SOX404）與管理當局盈餘預測之關聯性，係美國S&P500之公司為研究對象，研究期間為2002年至2009年，主要檢測：(1)相對於SOX 404而言，在SOX 302規範下揭露無內部控制缺失之公司，其管理當局盈餘預測準確度是否會較低。(2)在SOX 404之規範下揭露有內部控制缺失之公司，公司層級的內部控制缺失相較於會計層級的內部控制缺失，是否會導致管理當局盈餘預測準確度較低。 本研究之實證結果顯示：(1)在無內部控制缺失情況下，相對於SOX 404而言，在SOX 302規範下，管理當局盈餘預測準確度會較低。(2)在SOX 404之規範下揭露有內部控制缺失之公司，公司層級的內部控制缺失相較於會計層級的內部控制缺失，會導致管理當局盈餘預測準確度較低。 / The main purpose of this thesis is to investigate the relation among SOX302, SOX404 and the accuracy of management earnings forecasts. Using a sample of S&P listed companies during the period 2002-2009, I address the following issues: (1) whether companies with effective internal controls under SOX302 have lower earnings forecast accuracy, compared with those under SOX404; (2) in the SOX404 context, whether companies with firm-level material weaknesses have lower earnings forecasts accuracy, compared with those with account-specific material weaknesses. As predicted, my empirical results show that: (1) compared with those under SOX404, companies with effective internal controls under SOX302 have lower earnings forecasts accuracy; (2) compared with those that disclosed account-specific material weaknesses under SOX404, the companies with firm-level material weaknesses have lower earnings forecasts accuracy.