Provided are surface-modified metals such as metal medical devices e.g., guide wires, syringe needles, and metal tubes in medical devices or equipment, and methods for modifying a metal surface, wherein a lubricant layer is firmly bonded to the surface to impart lubricity to the surface and, further, improve the durability of the lubricant layer on the surface, thereby suppressing deterioration of the sliding properties. Included is a surface-modified metal having a surface at least partially treated by polymerization of a monomer in the presence of a thermal polymerization initiator.