Clad Electrode for Spark Plug and Method For Manufacturing Same

A clad electrode for a spark plug used as an center electrode and a ground electrode of a spark plug composed of a precious metal tip arranged at the leading end of a spark plug and a base material to which the precious metal tip is joined, wherein a junction interface between the precious metal tip and the base material is substantially planar, and a 5 μm to 100 μm-thick diffusion layer is formed in the joined part of the clad electrode. This clad electrode is manufactured with placing the joining face of a substantially columnar precious metal tip in abutting contact with a surface of the base material, preliminarily joining the precious metal tip to the surface of the base material with resistance welding, punching out a part in which the base material and the precious metal tip are integrated with each other, and diffusion-joining the base material and the precious metal tip with heat treatment.