<p>In a friction agitation joining method for joining metallic joining members, a joining device (3) having a column-shaped rotor (30) of a larger diameter and a pin-shaped probe (32) of a smaller diameter integrally formed on an end of the rotor (30) and protruded along an axis of the rotor (30) is used for joining the metallic joining members (1)(2). The probe (32) is rotated and inserted into or around a butted portion of the joining members (1)(2) to soften a contact portion contacted by the probe (32) by friction heat and to agitate the contact portion so that the joining members (1)(2) are butt joined. Each joining member (1)(2) has a thick portion (10)(20) at a butting side thereof. The rotating rotor is contacted to the thick portions (10)(20) under pressure to soften the thick portions (10)(20) by friction heat so that a gap formed at the butted portion is filled with the materials of the softened thick portions (10)(20). <IMAGE> <IMAGE> <IMAGE></p>
