Using the synchrotron photoemission spectroscopy, the band-bending, the work-function and the valence band edge were simultaneously monitored at the initial stages of Sb growth on Si(100) held at 60 K. By the intensity attenuation of Si 2p with increasing Sb coverage, it can be deduced that Sb forms a relatively uniform overlayer on Si(100) at 60 K. The band-bending, determined by the bulk Si 2p position, oscillates within 0.15 eV up to about 4 ML of Sb, while the corresponding work-function, monitored by the secondary-cutoff position of biased substrate, negligibly changes. The metallicity, monitored by the valence band edge, indicates that the surface becomes semiconductor-like up to about 1.5 ML but recovers its metallic character with additional Sb coverage. These results implicate that the oscillating band-bending is due to the local charge exchange between the dimer row and Sb at the interface, while the corresponding metallicity of Sb film is determined by the amount of confined and available charges within the film.