A metal member comprising: a first plate; and a second plate abutting against and welded to the first plate in at least one butt portion (S2, S3), wherein in the butt portion (S2, S3), a length from a first end to a second end of a welding boundary line between the first plate and the second plate is longer than a length of a straight line connecting the first end to the second end of the welding boundary line; wherein: the at least one butt portion (S2, S3) includes a first butt portion, a second butt portion, and a curved portion in which the first plate and the second plate abut against and are welded to each other; a first welding boundary line between the first plate and the second plate is present in the first butt portion; a second welding boundary line between the first plate and the second plate is present in the second butt portion; the curved portion is interposed between the first butt portion and the second butt portion and connects the first butt portion and the second butt portion to each other; and the second welding boundary line is a shortest line connecting a first end and a second end of the second welding boundary line to each other along a surface of the second plate; wherein: the second butt portion includes a bent portion having a bending line perpendicular to the second welding boundary line; and the first welding boundary line and the curved portion are on the same side with respect to the bending line such that the second welding boundary line is parallel to a direction in which the metal member is removed from a bending die after bending; and wherein: the second end of the first welding boundary line is an opposite end of the first welding boundary line from the curved portion and is present at a first end of the first plate and at a first end of the second plate, the first end of the first plate and the first end of the second plate providing an edge of the metal member that extends in a direction perpendicular to the bending line; and the second end of the second welding boundary line is an opposite end of the second welding boundary line from the curved portion and is present at a second end of the first plate and a second end of the second plate, the second end of the first plate and the second end of the second plate providing an edge of the metal member that extends in a direction parallel to the bending line. a first plate; and a second plate abutting against and welded to the first plate in at least one butt portion (S2, S3), wherein in the butt portion (S2, S3), a length from a first end to a second end of a welding boundary line between the first plate and the second plate is longer than a length of a straight line connecting the first end to the second end of the welding boundary line; wherein: the at least one butt portion (S2, S3) includes a first butt portion, a second butt portion, and a curved portion in which the first plate and the second plate abut against and are welded to each other; a first welding boundary line between the first plate and the second plate is present in the first butt portion; a second welding boundary line between the first plate and the second plate is present in the second butt portion; the curved portion is interposed between the first butt portion and the second butt portion and connects the first butt portion and the second butt portion to each other; and the second welding boundary line is a shortest line connecting a first end and a second end of the second welding boundary line to each other along a surface of the second plate; the at least one butt portion (S2, S3) includes a first butt portion, a second butt portion, and a curved portion in which the first plate and the second plate abut against and are welded to each other; a first welding boundary line between the first plate and the second plate is present in the first butt portion; a second welding boundary line between the first plate and the second plate is present in the second butt portion; the curved portion is interposed between the first butt portion and the second butt portion and connects the first butt portion and the second butt portion to each other; and the second welding boundary line is a shortest line connecting a first end and a second end of the second welding boundary line to each other along a surface of the second plate; the second butt portion includes a bent portion having a bending line perpendicular to the second welding boundary line; and the first welding boundary line and the curved portion are on the same side with respect to the bending line such that the second welding boundary line is parallel to a direction in which the metal member is removed from a bending die after bending; and the second end of the first welding boundary line is an opposite end of the first welding boundary line from the curved portion and is present at a first end of the first plate and at a first end of the second plate, the first end of the first plate and the first end of the second plate providing an edge of the metal member that extends in a direction perpendicular to the bending line; and the second end of the second welding boundary line is an opposite end of the second welding boundary line from the curved portion and is present at a second end of the first plate and a second end of the second plate, the second end of the first plate and the second end of the second plate providing an edge of the metal member that extends in a direction parallel to the bending line.