During the process of transporting an electronic component (18) to a substrate (10) after a suction nozzle (7) has picked up the component (18), the component (18) being supplied from a component supply unit (1), the amount of offset of the component (18) with respect to the suction nozzle (7) is calculated. The feasibility of mounting the component (18) held by the suction nozzle (7) onto the substrate (10) without hindrance is determined from the amount of offset. If the result of the determination is positive, the component (18) is mounted onto the substrate (10).