A corrosion protection cathode using an external power supply in which a reinforcing layer formed of a fiber base material is laminated with an adhesive layer on one surface of a conductive layer formed of a graphite sheet, and an electrolyte layer of an electrolyte-containing resin formed in a sheet shape and having adhesive power such that the layer is capable of being adhered to the conductive layer and to a surface layer of an object to be protected from corrosion is adhered by the adhesive power thereof to the other surface of the conductive layer, wherein the conductive layer always has a resistance value of 4Ω or less between any two points on the surface thereof on a side that comes into contact with the electrolyte layer.