Weld structures of metal members include: a first member; and a second member that is layered together with the first member, wherein at least one first solidified part that extends from a surface of the first member to the inside of the first member, at least one second solidified part that is formed by a molten area extending through the first member and the second member, and at least one third solidified member that is formed by a molten area extending through the first member and the second member are provided, and the third solidified part is located closer to a non-layered surface of the second member than the second member is. Further disclosed are welding processes for producing the same.