A transfer rack 15 loaded with a seriate number of component supply cassettes 14 to be handled collectively is carried and retained on a truck 61 so that it can be taken in and out of the truck 61. The transfer rack 15 is passed between the truck 61 and a component supply section 8. Thus, the withdrawal of the transfer rack 15 from the component supply section 8 to the truck 61 and the delivery of the transfer rack 15 to the component supply section 8 are executed in a timely manner so as to change the component supply cassettes 14 at the component supply section 8. The transfer rack 15 delivered to the component supply section 8 is positioned by operating an automatic positioning means at the component supply section 8 in a direction in which it is loaded and unloaded and in a direction perpendicular to the direction in which it is loaded and unloaded.