A data volume of a data transferred from a ROM to a RAM corresponds to a data volume specified by a data volume information included in a program data. By setting the data volume specified by the data volume information as the data volume of the program data to be transferred, only the program data having the data volume specified by the data volume information can be transferred from the ROM to the RAM. Therefore, an excessive data transfer may not be performed, and the time required for booting a system may not be increased. Also, only by changing the data volume specified by the data volume information, the data volume of the data to be transferred to the RAM can be arbitrarily changed. Therefore, the flexibility to create a program or a program for upgrade is expanded, and a burden imposed on a creator is reduced.