In a case where check unnecessary components (chip components a to c) that do not require checking of the mounted states of the other components before being mounted and check necessary components (die components X and Y) that require checking of the mounted states of the other components before being mounted are mounted on a board, the check unnecessary components are mounted first and the mounted state of each component is inspected. When mounting of the check unnecessary components is completed, the check necessary components are mounted after it is checked that the mounted states of the check unnecessary components are normal based on the inspection results.