PURPOSE: To quickly execute the backup processing of a data when a feed from a main power source is stopped, by updating the data of a semiconductor file so that its data can be saved successively in a nonvolatile data store means.

CONSTITUTION: At the time of storing a data in a semiconductor file 13, this data is stored in a nonvolatile data store means 9, as well. In such state, when the data of the semiconductor file 13 are updated, at the time of storing this data in the nonvolatile data store means, when a feed from a main power source is stopped, the backup processing of the data is executed by taking in power from a power source 16 for a backup. In such way, when a feed to a device is stopped, the backup processing of the data can be quickly executed.