Field emission characteristics from n- and p-type silicon gated emitter tips have been investigated in detail by means of experiments and theoretical estimation of band-bending induced by surface states. Single-tip emitters have been fabricated from n- and p-type silicon and their current-voltage characteristics have been evaluated. The field emission from the p-type emitter has been found to occur at lower extraction voltage than that of the n-type emitter. As the theoretical approach to the origin of the phenomena, potential distribution in the emitter tips has been calculated by using device simulation technique. The surface states of the n-type emitter tip are negatively charged and form a potential barrier against the electrons. On the contrary, there is no potential barrier in the p-type tips. The potential barrier in the n-type tip prevents electrons from reaching the tip apex. This is the reason why the emission current of the n-type emitter was suppressed lower than that of the p-type emitter.