To provide a joint shape obtaining a satisfactory weld zone by suppressing the generation of the gap of a joint part by welding when the welding of a member is performed by the friction-stirr-welding.

The butted surface of the weld zone of the members 10 and 11 must be an inclined surface 12. The friction-stirr-welding is performed from an upside. The welding is performed so that the inclined surface 12 is positioned, connecting to or coming close to welding beads. Since there is the inclined surface 12, the flowing out of the members can be suppressed, and the bend of the weld zone, can be suppressed. The welding is performed by arranging tabs at the start edge and the terminal edge of the welding.