Abstract the purpose of this study is to determine the effect of audit firm size and earnings management towards the cost of equity capital either simultanously or partially on listed companies of the manufacturing sector in indonesian stock exchange in the period 2009-2011. the type of this study is causality with purposive sampling method and unbalanced panel data. the samples of this study are 73 companies with 219 observational data. the type of data used is secondary data, which is the financial statement obtained from the official website of indonesian stock exchange. the research hypotheses is analyzed using multiple regression analysis model. the result of this research shows that audit firm size and earnings management simultanously affect the cost of equity capital, audit firm size affect the cost of equity capital, and earnings management also affect the cost of equity capital. keywords: audit firm size, earnings management, cost of equity capital