An electronic device includes an operation processing unit, a main storage unit, a program storing ROM for storing a plurality of divided program codes and for storing loading program codes for loading the program codes to the main storage unit, an information table storing ROM for storing an information table having a description of information about the program codes to be loaded from the program storing ROM to the main storage unit, and a map management element having a description of virtual addresses in the main storage unit at which the program codes stored in the program storage element are mapped. As a result of this construction, only those program codes requiring quick response are loaded without loading all the program codes to the main storage unit and executed promptly, and thus the system activation time can be reduced.