We consider the feedback effects of the early reionization on the formation of small galaxies. For this purpose, we perform 3D radiation hydrodynamic simulations with incorporating the radiative transfer for ionizing photons. As a result, it is found that the early reionization is so devastating for low mass systems with $M_{\rm vir} \lesssim 10^8 M_\odot$ or $v_{\rm circ} \lesssim 20 {\rm km/s}$, and almost all gas is photo-evaporated in more than 95% of low mass systems. These results indicate that the low mass dwarf galaxies are not formed directly from isolated CDM density perturbations.