An electrode substrate includes a substrate and an electrode layer of a noble metal crystal formed on the substrate, the noble metal crystal exhibiting a substantially linear domain boundary and a plane orientation dispersion angle in X-ray analysis of 1.degree. or less. An information recording medium includes an electrode substrate as described above and a recording layer provided on the electrode layer. An information processing apparatus includes: an information recording medium as described above; a probe electrode arranged in close proximity to this medium; and a voltage applying circuit for applying a pulse/bias voltage between the medium and the probe electrode, information being written/read onto/from the medium by the application of the pulse/bias voltage. An information processing method includes the steps of: preparing an information recording medium as described above; arranging a probe electrode in close proximity to the medium; and applying a pulse/bias voltage between the medium and the probe electrode so as to write/read information onto/from the medium.