Electric field induced resistance switching and memory effect has been investigated for perovskite-oxide heterojunctions consisting of various metal electrodes and p-type or n-type semiconducting perovskite oxides such as Pr_0.7Ca_0.3MnO₃ and Nb-doped SrTiO₃(Nb : STO). The metal/perovskite-oxide heterojunction devices show either ohmic or rectifying current-voltage (I-V ) characteristics similar to those of a Schottky junction, depending on the work function of the metals. In addition, the rectifying I-V characteristics have large hysteresis that can host the resistance switching effect. The dependence of the I-V characteristics on the Nb-doping level in the heteroepitaxial SrRuO₃/Nb : STO junctions suggests that the threshold of resistance switching is determined by the potential profile of the Schottky barrier under bias voltage. From the experimental results, we propose the possible origin of the resistance switching effect, that is a charging effect at the Schottky-like metal/perovskite-oxide interfaces.