PURPOSE: To obtain a memory device for providing an information processor which can improve the reliability of data saved in a battery backup memory at the time of a momentary power break and reduce the size and cost of its power unit.

CONSTITUTION: This memory device is equipped with a parity calculation unit 9 which generates an error detection code and an error correction code at a high speed for data saved in the memory device 3 in case of a momentary power break and detects and corrects an error when the power supply recovers, an MISR, an LFSR, and a controller 8. Consequently, the error detection code and error correction code are generated fast in case of the momentary power break, so the capacity of a capacitor bank which maintain the circuit power supply may be small. The error correction and error detection are performed fast, so movement to stationary information processing at the time of the power recovery can be quickened.