Joint part and manufacturing method therefor

A manufacturing method for a joint part in which a first metal piece and a second metal piece are joined to each other by performing welding by irradiating a high-energy beam to a joint surface on which the first metal piece and the second metal piece face each other, the first metal piece including a first flow path for passage of a fluid provided at a specific depth from a surface on a side exposed to the high-energy beam, the second metal piece including a second flow path for passage of the fluid provided at a specific depth from the surface on the side exposed to the high-energy beam, and the first flow path and the second flow path being coupled to each other on the joint surface, the manufacturing method comprising:

• performing a first welding in which welding is performed at a fusing depth that does not reach a coupling between the first flow path and the second flow path in a first range of the joint surface, the first range including a specific portion that overlaps the coupling as seen from the surface side that is exposed to the high-energy beam;
• and
• performing a second welding in which welding is performed at a fusing depth that is larger than the fusing depth of the first welding in a second range of the joint surface, the second range excluding the specific portion.