A memory management apparatus for a vehicle, which is mounted on the vehicle, the apparatus comprising: a volatile memory to which power source is continuously supplied and having a diagnostic trouble code storage area having a plurality of storage areas each storing only one diagnostic trouble code; a nonvolatile memory having a backup area for storing the same code as the diagnostic trouble code; and a storage control unit (S140-S180, S240, S340), when a fault is detected in a predetermined object to be detected in the vehicle, for storing the diagnostic trouble code indicative of the detected fault as a determined diagnostic trouble code into the diagnostic trouble code storage area, and storing the determined diagnostic trouble code configured to be stored in the backup area from among the determined diagnostic trouble codes into the backup area as a permanent diagnostic trouble code (PDTC), wherein the volatile memory further includes a mirror area for storing same information as information in the backup area, the storage control unit (S140-S180, S240, S340) further stores the same code as the permanent diagnostic trouble code (PDTC) into the mirror area, and a recovering unit (S230, S260, S350) is provided, for updating information in one of the mirror area and the backup area by a predetermined recovering process so that the information in the mirror area and the information in the backup area match with each other; characterized in that the volatile memory further includes an update information storage area for storing update information indicative of a data update status in the volatile memory; the storage control unit (S140-S180, S240, S340) being adapted to store the update information into the update information storage area; said recovering unit (S230, S260, S350) being adapted to update information in one of the mirror area and the backup area by the predetermined recovering process on a basis of the update information stored in the update information storage area; and the recovering unit (S230, S260, S350) executes, as the recovering process, a first process of copying the information in the mirror area into the backup area 30 when it is determined on the basis of the update information that the information in both of the mirror area and the diagnostic trouble code storage area is updated, and executes, as the recovering process, a second process (S260, S350) of copying the information in the backup area into the mirror area when it is determined on the basis of the update information that the information in at least one of the mirror area and the diagnostic trouble code storage area is not updated. a volatile memory to which power source is continuously supplied and having a diagnostic trouble code storage area having a plurality of storage areas each storing only one diagnostic trouble code; a nonvolatile memory having a backup area for storing the same code as the diagnostic trouble code; and a storage control unit (S140-S180, S240, S340), when a fault is detected in a predetermined object to be detected in the vehicle, for storing the diagnostic trouble code indicative of the detected fault as a determined diagnostic trouble code into the diagnostic trouble code storage area, and storing the determined diagnostic trouble code configured to be stored in the backup area from among the determined diagnostic trouble codes into the backup area as a permanent diagnostic trouble code (PDTC), wherein the volatile memory further includes a mirror area for storing same information as information in the backup area, the storage control unit (S140-S180, S240, S340) further stores the same code as the permanent diagnostic trouble code (PDTC) into the mirror area, and a recovering unit (S230, S260, S350) is provided, for updating information in one of the mirror area and the backup area by a predetermined recovering process so that the information in the mirror area and the information in the backup area match with each other; characterized in that the volatile memory further includes an update information storage area for storing update information indicative of a data update status in the volatile memory; the storage control unit (S140-S180, S240, S340) being adapted to store the update information into the update information storage area; said recovering unit (S230, S260, S350) being adapted to update information in one of the mirror area and the backup area by the predetermined recovering process on a basis of the update information stored in the update information storage area; and the recovering unit (S230, S260, S350) executes, as the recovering process, a first process of copying the information in the mirror area into the backup area 30 when it is determined on the basis of the update information that the information in both of the mirror area and the diagnostic trouble code storage area is updated, and executes, as the recovering process, a second process (S260, S350) of copying the information in the backup area into the mirror area when it is determined on the basis of the update information that the information in at least one of the mirror area and the diagnostic trouble code storage area is not updated.