Early research on firm value was conducted, while the result still discussed. Research on ROA as a one of financial measurement has positive effect on firm value, while others were shown negative. This condition drive us to use Good Corporate Governance (GCG) disclosure as mediation variable. This research examine the role of GCG on mediating relationship between financial performance and firm value.

 This research use 27 manufacture firm that listed on JSX during 2006 - 2007 as sample with 54 observation, we use regression to see the role of GCG. Tobin's Q uses for measure firm value, while GCG measured by ownership management index, and we use ROA to measure financial performance.

 Result shown that ROA has positive impact on firm value, and disclosure of GCG has no mediation role on relationship between ROA and firm value.

Keywords :     Financial Performance, Return on Asset, Firm Value, Good Corporate Governance.