This substrate includes an insulating substrate having a first surface and a second surface, and a metal layer of a metal plate bonded to the first surface. The insulating substrate has a through hole. The metal layer includes: a bent section that is inserted through the through hole and bulges from the first surface toward the second surface; and outer periphery sections that are positioned around the bent section and are bonded to the first surface. The bent section has a first end and a second end positioned on opposite sides, and is bent with respect to the outer periphery sections at the first end and the second ends. The outer periphery sections are divided into a first outer periphery section and a second outer periphery section, which are respectively continuous with the first end and the second end of the bent section.