A component mounting station is divided into two component mounting areas in a board conveyance direction according to the size of circuit boards used in two types of production that are performed in order, and the area in which a backup pin is arranged on a backup plate is divided into two pin arrangement areas corresponding to the two component mounting areas. The quantity of backup pins necessary to support the component mounting board are arranged in a predetermined arrangement pattern, the circuit boards transported using the conveyor are stopped in the component mounting areas according to the type of component mounting board produced, the backup plate is lifted up, and the circuit boards are clamped by the clamp member, and the circuit boards supported by the backup pins in the pin arrangement areas are positioned below the circuit boards, and components are mounted on the circuit boards.