In a device for attaching a component supply unit 11 to a component mounting machine 20 by inserting the component supply unit 11 into a unit attachment space 21 of the component mounting machine 20, the component mounting machine 20 includes unit-raising devices 52 that raise the component supply unit 11 inserted into the unit attachment space 21, unit pull-in devices 61 that pull the component supply unit 11, which has been raised by the unit-raising devices 52, into the component mounting machine 20, and clamp pawls 57 that lower the component supply unit 11, which has been pulled in by the unit pull-in devices 61, to a predetermined height position by the unit-raising devices 52, and clamp the component supply unit 11. Each of casters 24, which support the component supply unit 11 so as to allow the component supply unit 11 to be movable up and down, is provided with a spring or the like that assists a force for raising the component supply unit 11 generated by the unit-raising devices 52.