The present invention relates to a friction stir welding head including a central pin shaft, a peripheral shoulder part, a shaft for driving in rotation the part and the shaft about the axis, the shaft being integral in rotation with the part and being free in translation with respect to the part along the axis, the head including an external interface part intended to be secured to a rotary spindle of the machine, a device for transmitting the rotation of the shaft about the axis of rotation from the part and a device for driving in translation the shaft along the axis from the motor during the rotation of the shaft and of the part.