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 a 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 a 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.