A plating apparatus for plating a cylinder block includes a cylindrical electrode disposed in a cylinder bore of the cylinder block integrated with a cylinder head, in which a cylinder inner-peripheral surface of the cylinder bore is subjected to pre-plating or plating process by introducing a treatment liquid into a gap between the cylinder inner-peripheral surface and an outer-peripheral surface of the cylindrical electrode and into an inside of the cylindrical electrode and by energizing the cylindrical electrode and the cylinder block. The cylinder head is formed with a combustion chamber communicating with the cylinder bore, and a seal member for sealing the combustion chamber is mounted on the cylindrical electrode so as to be disposed in the combustion
