A method and a system for updating software stored in a flash memory, which enables a user to resume a suspended updating process even when log data stored in a journaling area is lost. According to the present invention, log data indicating the results of implementation of each step of the updating process is stored in a journaling area allocated in a flash memory to update the software. The data stored in the journaling area is copied into a first backup journaling area allocated in the flash memory whenever each step is completed. Concurrently, log data indicating the copying results is stored in a second backup journaling area.