A method for mounting electronic components on circuit boards by operating an electronic component-mounting apparatus based on numerical control (NC) data involves the storage of component information, including supply numbers of components purchased from a plurality of makers, maker names of the purchased components, sizes thereof, configurations thereof, and mounting conditions, into a component mounting data base. A correspondence is established between factory numbers listed in a CAD data table and the supply numbers, thereby allowing the management of the supply numbers by grouping one or more supply numbers with each factory number. The supply numbers corresponding to a factory number are used as an index to obtain component information corresponding to each of the supply numbers. This obtained component information is used to generate the numerical control (NC) data for the component-mounting apparatus.