本研究旨在探討管理當局自願性盈餘預測與權益資金成本之關聯性，檢視管理當局發布盈餘預測頻率之影響是否反應於權益資金成本上，並進一步檢視管理當局之聲譽是否為影響權益資金成本的因素之一。 在本研究的實證分析結果中，發現管理當局發布自願性盈餘預測之頻率與權益資金成本呈顯著負相關，表示管理當局發布盈餘預測的次數越多時，權益資金成本越低。 在管理當局聲譽對於權益資金成本的影響，本研究實證分析結果發現，管理當局之聲譽與權益資金成本亦呈顯著負相關，管理當局聲譽以管理當局預測誤差和分析師預測誤差來衡量，當管理當局的盈餘預測誤差小於分析師盈餘預測誤差時，投資人認為管理當局對盈餘的預測有效且值得信賴，此時管理當局聲譽提高，投資人認為取得有用的資訊，進而降低企業權益資金成本。 / The primary objective of this thesis is to explore whether the frequency of management forecasts is related to the cost of equity capital. In addition, I further examine whether the association is stronger when management has better reputation. Basing on a sample of S&P 500 listed firms during 2000-2009, I find that, consistent with my prediction, cost of firm’s equity capital decreases with the frequency of management earning forecasts after controlling for other determinants well-documented to be related to cost of equity capital. Second, I find that cost of equity capital is negatively related to the reputation of management; however, I do not find that the association between cost of equity capital and the frequency of management systematically vary with the reputation of management.