Provided is an electrode (1) which has a double structure including Cu or a Cu alloy as an electrode body (2) and a core material (3) made of W, Mo, a W-based alloy, or a Mo-based alloy embedded in a surface of the electrode body (2) which is abutted against a material to be welded, the core material (3) being formed by using W, Mo, the W-based alloy, or the Mo-based alloy which is in the form of a fibrous structure extended by sintering, swaging, and annealing in an electrode axis direction, the fibrous structure having a horizontal cross-sectional average particle diameter of 50 μm or more and an aspect ratio of 1.5 or more. The electrode (1) can be used as an inexpensive electrode obtained by suppressing particle dropping / attrition and defects in electrodes for spot welding, in which heat and pressure are applied repeatedly, stably enhancing durability.