Joining method and joined body

A welding method comprising:

• creating an overlapping part where a first member and a second member overlap so that a lower surface of the first member is in contact with an upper surface of the second member, the overlapping part including one end and another end;
• forming a first friction-stirred part at a one-end-side spot that is a spot that is closest to the one end of the overlapping part by plunging a rotary tool into the one-end-side spot from the first member;
• forming a second friction-stirred part at an other-end-side spot that is away from the one-end-side spot and closer to the other end of the overlapping part by plunging the rotary tool into the other-end-side spot from the first member after the first friction-stirred part is formed;
• and
• forming a third friction-stirred part at an intermediate spot between the one-end-side spot and the other-end-side spot by plunging the rotary tool into the intermediate spot of the overlapping part from the first member after the second friction-stirred part is formed,
• wherein the rotary tool is plunged into each of the spots so that an input heat amount to the one-end-side spot and an input heat amount to the other-end-side spot are smaller than an input heat amount to the intermediate spot.