Whether an anomaly occurs in a data-rewritable second nonvolatile memory is determined by comparison between (i) a diagnosis code stored in the second nonvolatile memory and (ii) data contents stored as a diagnosis table in a first nonvolatile memory. The first nonvolatile memory previously stores the diagnosis table for listing diagnosis codes. If the diagnosis codes are appropriately registered in the diagnosis table, it is thereafter unnecessary to take into consideration whether the diagnosis codes are normally stored in the first nonvolatile memory. This configuration requires no further rewriting of information in the first nonvolatile memory unlike other memories, and thus decreases a possibility of an occurrence of an anomaly to garble the information in the first nonvolatile memory in comparison with other memories. Whether an anomaly occurs in the second nonvolatile memory can be thus performed more appropriately.