The present invention relates to a biomolecule-based electronic device in which the biomolecule with redox potential is directly immobilized on the substrate. The present invention enables to excellently exhibit the capability of a protein-based bio-memory device in which it is preferable to use the substrate on which cysteine-introduced recombinant proteins are effectively immobilized and a self-assembled layer (SAM) is fabricated. It becomes realized that a redox potential is regulated using intrinsic redox potential of the protein dependent on applied voltage. The present invention provides a novel operating method in which three potentials are applied throughout four steps. The present invention has some advantages of fabricating a protein layer in a convenient manner and inducing electron transfer by fundamental electrochemical or electronic operation. The method of this invention is considered as a new concept in the senses that intrinsic electron transfer mechanisms induced by natural-occurring biomolecules are used to develop an information storage device.