Method of manufacturing joined body

A method of manufacturing a joined body, the method comprising:

• placing a first plate portion and a second plate portion that are plate-shaped portions such that the first plate portion and the second plate portion are stacked one on top of another in their plate thickness directions;
• and
• thereafter joining the first plate portion and the second plate portion together by heating a region to be heated that is located along a weld line from a second plate portion side of the first plate portion and the second plate portion that are stacked, thereby forming a weld bead that extends from a starting end to a terminal end of the weld bead while forming a penetration portion that extends from the second plate portion to the first plate portion in a region where the weld bead is formed,
• wherein the weld bead includes a first weld portion, a second weld portion, and a third weld portion, each forming a respective part of the weld bead,
• wherein the first weld portion and the second weld portion are formed continuously such that a terminal end of the first weld portion coincides with a starting end of the second weld portion, and a part of the second weld portion that is different from the starting end of the second weld portion is formed at a position that overlaps a part of the first weld portion, whereby the first weld portion and the second weld portion form a loop portion that is a loop-shaped weld portion, and
• wherein, in the third weld portion, the second weld portion and the third weld portion are formed continuously such that a terminal end of the second weld portion coincides with a starting end of the third weld portion, and a terminal end of the third weld portion that is the terminal end of the weld bead is formed on an inner peripheral side of the loop portion,
• the method further comprising carrying out control for reducing amounts of heat such that an amount of heat supplied to the region to be heated during formation of the third weld portion is smaller than an amount of heat supplied to the region to be heated during formation of the first weld portion.