This member includes a first sheet material and a second sheet material overlapped with the first sheet material, and the first sheet material and the second sheet material are joined to each other at an interface therebetween by three joint line portions. A first joint line portion includes an A portion whose shortest in-plane distance from a second joint line portion is 20 times or more and 120 times or less a sheet thickness of the first sheet material, a second joint line portion includes a B portion whose shortest in-plane distance from the first joint line portion is 20 times or more and 120 times or less the sheet thickness of the first sheet material, a third joint line portion is in a region interposed between the A portion and the B portion, and has a length of a length component of 250 mm or more in an extension direction of an intermediate line between the first joint line portion and the second joint line portion.