Abstract: An electric-component mounting system including a component-holding device for holding an electric component, a board-supporting device for supporting a printed-wiring board on which the electric component is mounted, a first relative-movement device operable to move the component-holding device and the board-supporting device relative to each other in a first direction parallel to a surface of the board supported by the board-supporting device, a second relative-movement device operable to move the component-holding device and the board-supporting device relative to each other in a second direction which intersects the surface of the board; and a control device including a positioning portion operable to select one of a plurality of different control targets which is used for the first relative-movement device to establish a predetermined relative position between the component-holding device and the board-supporting device, and wherein the positioning portion selects one of the different control targets, de