Abstract: A flux is supplied from a flux transfer head having a flux transfer pin to a predetermined position on a substrate, and then a solder ball is mounted on the predetermined position by a solder ball mounting head having a suction nozzle. The solder ball mounting head and the flux transfer head are provided alternately on a head supporter. When the rotation of the head supporter is stopped, sucking a solder ball suction by the suction nozzle, depositing the flux on a free end of the flux transfer pin, transferring the flux to the substrate by the flux transfer pin, and mounting the solder ball on the predetermined position by the ball mounting head, and examining whether the solder ball exists on the suction nozzle by which the ball mounting operation has just carried out are executed.