A welding method of applying energy to an interface where a metal glass and a crystalline metal make contact with each other or to the metal glass near the interface, heating and melting the metal glass to form a molten layer, and joining the metal glass and the crystalline metal. The metal glass has a glass formation ability in which a nose time of a TTT curve when a solid of the metal glass is reheated is 0.2 seconds or more. The metal glass and the crystalline metal are formed with a material that satisfies a temperature range of a temperature of the metal glass at which a spread factor of the crystalline metal that has not been melted and the molten metal glass is 25% or more and a melting point of the crystalline metal to be 100 K or more.