A method of producing a leadframe for use in semiconductor devices, comprises the steps of forming a space between leads 1a and 1b which are to be overlapped and welded each other, and welding the leads at a region including the space and melting and cutting off one of the leads. In one of the leads which is melted, cohesion and separation of molten metal occur in the region around the space. As a result, unnecessary portions such as an outer frame used for positioning can be cut off at the same time when the leads are connected by welding. Thus, high precision positioning of a plurality of element leadframes as well as high assembling productivity are achieved.