Recently, the conversion of corn to etanol (biofuel) in international market is currently exist and has an impact on the availability of corn in Indonesia. This study aims at: (1) the analysis of behavior of domestic and international market of corn, (2) the effect analysis of corn conversion to ethanol at international market on corn availability in Indonesia, and (3) the formulation of policies to increase domestic corn availability. Using time series data of 1983-2006 and econometric model of simultaneous equations estimated by employing the 2SLS procedure, the study found that: (1) there is a linkage between domestic and international market of corn through import price variable, (2) corn conversion to ethanol decrease the domestic availability of corn but increase the production share of corn availability in Indonesia, and (3) fertilizer subsidy and import tariff policy would increase corn production to allow thye increase of corn domestic production share on corn availability.