A double-action friction stir joining system, comprising: a double-action friction stir joining device; a cleaning mechanism having a dressing member; a robot; and a control device, wherein the double-action friction stir joining device includes: a pin member formed in a cylindrical shape and configured to be rotatable on an axis and reciprocatable in a direction along the axis; a shoulder member formed in a cylindrical shape, into which the pin member is inserted, and configured to be rotatable on the axis and reciprocatable in a direction along the axis; a first rotary driver configured to rotate the pin member and the shoulder member on the axis, respectively; a tool driver configured to reciprocate the pin member and the shoulder member along the axis, respectively, and a position detector configured to detect a position of a tip-end face of the pin member in the direction along the axis and output information of the detected position to the control device, wherein the control device is adapted to: operate the tool driver so that the pin member is thrusted into the shoulder member; operate the first rotary driver so that the shoulder member rotates; and operate the robot so that the robot holds the double-action friction stir joining device and the dressing member contacts an inner circumferential surface of the shoulder member, characterized in that the control device operates the tool driver in so that: a tip-end face of the pin member is moved to a first position set in advance; and the tip-end face of the pin member is moved to a second position set in advance, after, at a larger speed than in. a double-action friction stir joining device; a cleaning mechanism having a dressing member; a robot; and a control device, wherein the double-action friction stir joining device includes: a pin member formed in a cylindrical shape and configured to be rotatable on an axis and reciprocatable in a direction along the axis; a shoulder member formed in a cylindrical shape, into which the pin member is inserted, and configured to be rotatable on the axis and reciprocatable in a direction along the axis; a first rotary driver configured to rotate the pin member and the shoulder member on the axis, respectively; a tool driver configured to reciprocate the pin member and the shoulder member along the axis, respectively, and a position detector configured to detect a position of a tip-end face of the pin member in the direction along the axis and output information of the detected position to the control device, a pin member formed in a cylindrical shape and configured to be rotatable on an axis and reciprocatable in a direction along the axis; a shoulder member formed in a cylindrical shape, into which the pin member is inserted, and configured to be rotatable on the axis and reciprocatable in a direction along the axis; a first rotary driver configured to rotate the pin member and the shoulder member on the axis, respectively; a tool driver configured to reciprocate the pin member and the shoulder member along the axis, respectively, and a position detector configured to detect a position of a tip-end face of the pin member in the direction along the axis and output information of the detected position to the control device, wherein the control device is adapted to: operate the tool driver so that the pin member is thrusted into the shoulder member; operate the first rotary driver so that the shoulder member rotates; and operate the robot so that the robot holds the double-action friction stir joining device and the dressing member contacts an inner circumferential surface of the shoulder member, operate the tool driver so that the pin member is thrusted into the shoulder member; operate the first rotary driver so that the shoulder member rotates; and operate the robot so that the robot holds the double-action friction stir joining device and the dressing member contacts an inner circumferential surface of the shoulder member, characterized in that the control device operates the tool driver in so that: a tip-end face of the pin member is moved to a first position set in advance; and the tip-end face of the pin member is moved to a second position set in advance, after, at a larger speed than in. a tip-end face of the pin member is moved to a first position set in advance; and the tip-end face of the pin member is moved to a second position set in advance, after, at a larger speed than in.