The invention provides a welding method by resistance welding capable of adequately increasing a welding strength between two conductive terminals each made of copper, and a conductive terminal structure obtained by the method. A first conductive terminal made of a tinned flat copper plate is molded such that a step portion is formed at a position spaced away from a tip end position of the first conductive terminal and a projection is formed at a tip end portion ranging from the tip end position to the step portion. A second conductive terminal made of the aforementioned copper plate and the first conductive terminal are molded such that a weld surface of the second conductive terminal has a size to cover an entire weld surface of the projection of the first conductive terminal. Simultaneously, the respective conductive terminals are molded such that the tip end portion of the first conductive terminal becomes substantially equal in sectional area to a weld portion of the second conductive terminal. These conductive terminals are brought into contact under pressure with electrodes equal in electrical characteristic to each other, and then electric current is fed to the electrodes. Thus, the projection of the first conductive terminal is melted into and is welded to the weld surface of the second conductive terminal.