We study nucleation of amphiphilic molecules in a solvent-amphiphile binary solution by Monte Carlo simulation. The method provides detailed information on the free energetics of micelle formation. Our model, despite its simplicity, captures various aspects of real amphiphilic solutions. For example, the density profiles exhibit typical micelle structure. The free energy surface for micelle formation is in line with recent molecular dynamics simulations. From the free energy surface, we identified the critical micelle concentration (CMC), above which the free energy barrier for micelle formation is at most 6k(B)T for the model we study.