The conflict of interest between managers (agents) and the owner (principals) occurs all the time, although the level of the conflict is not always similar. This is because there are separation roles or a difference of interests. In many Indonesian banks, the implementation of Good Corporate Governance (GCG) is mandatory. But, in manufacturing companies in Indonesia, GCG is still not a must. So, what is the role of GCG in conjunction with firm value in manufacturing companies? In addition, many manufacturing companies use earnings management as a benchmark of firm value. It is clear that earnings management can be placed as an antecedent of firm value. The purpose of this research is to analyze the determinants of firm value in relation to earnings management and the mechanism of GCG as a moderating variable. The GCG is not viewed as an antecedent variable. The research sample is 46 companies in the entire industry of consumer goods of manufacturing companies in the Indonesia Stock Exchange. By specific considerations, the number of the sample is reduced to 39 out of 46 companies. The method used is a moderated regression analysis (MRA). The results show that the earnings management and the mechanism of GCG have an impact on the firm value. The dimension of GCG, namely, independent commissioner, managerial ownership, and audit quality can be placed as moderating variables and as determinants of firm value. In order to increase the firm value, it is advisable that this industry should strictly apply the mechanism of GCG as mandatory. However, the issue of GCG as an independent or moderating variable still remains debatable.
