The present invention discloses a technique for updating information with respect to a DVD player, for example. When information to be updated such as a password for a parental lock or type of language is to be modified, the information to be updated is written into a free space within an area of the flash memory. Further, when the control delay becomes unnoticeable, information last written in the area of the flash memory is read out to be written into a temporary storage while the area of the flash memory is cleared. Then, the updated information in the temporary storage is written into the cleared area of the flash memory.