We will present the effect of an electric field on the growth from a reconstructed diamond(100) monohydride with mechyl radical of CH3 with a growth species, which was examined at the ab initio density functional cluster calculation of the B3LYP theory. First of all, activation energies of various reaction steps involving in this growth under a non-uniform electric field, which is calculated using the electron orbital energies and vibration frequencies of these various reaction steps via the ab initio cluster calculation on cluster models, C9H14 and C38H40, will be compared to activation energies without an electric field. Finally, we will address that the non-uniform electric field can drastically change the surface reaction pathway by modifying the electronic structures and vibration frequencies, which corresponds to the modification of activation energies of various reaction steps involving in this growth.