A method of joining a plurality of members to be joined together, by piling the plurality of members on one another and joining together the members with one another at end portions of superposed parts of the members, wherein the superposed parts of the members are held by restraining the superposed parts from both sides thereof, while a pressing tool, which is harder than the members, is pressed to end faces of the superposed parts and the pressing tool is rotated and/or moved relative to the superposed parts, so that the end faces of the superposed parts are rubbed to cause a friction heating which leads to cause a plastic flow, whereby the plurality of the members are joined together at the end portions of the superposed parts thereof.