The present invention relates to a protein-immobilized membrane (14) including a cell membrane homologous layer (14A) and a protein (14B) immobilized to the cell membrane homologous layer (14A), where the protein contains cytochrome or a cytochrome complex. The present invention also relates to a method for forming a protein-immobilized membrane (14), and an enzyme-immobilized electrode and a biosensor (X1) provided with a protein-immobilized membrane (14). Preferably, the cell membrane homologous layer (14A) may contain a phospholipid polymer, and the protein (14B) may be CyGDH including an α subunit having a glucose dehydrogenase activity and cytochrome C having a function of electron transfer.