An electronic control device applicable to a vehicle, comprising a nonvolatile memory including a plurality of storage regions (31, 32), wherein the storage regions (31, 32) include: an information storage region (131, 132) for storing information, and a management information storage region (133, 134) for storing management information indicating a write state of information to the storage regions (31, 32), wherein the electronic control device is adapted so that: during a driving cycle, the management information storage region (133, 134) holds a start mark (133A, 134A) indicating a write start of the information, and during self-shutdown, the management information storage region (133, 134) holds a completion mark (133B, 134B) indicating a write completion of the information, and wherein the nonvolatile memory includes, separately from the storage regions (31, 32), a management information access flag storage region for storing access information indicating if there has been an access to the management information, wherein the electronic control device is adapted so that: during the driving cycle, the management information access flag storage region holds a start mark access flag indicating if there has been an access to a registration address of the start mark (133A, 134A), and during self-shutdown, the management information access flag storage region holds a completion mark access flag indicating if there has been an access to a registration address of the completion mark (133B, 134B), wherein the electronic control device is adapted so that record patterns of the management information storage region (133, 134) and the management information access flag storage region in a case where a battery disconnection abnormality has occurred are different from record patterns of the management information storage region (133, 134) and the management information access flag storage region in a case where a battery disconnection abnormality has not occurred, and the storage region (31, 32) stores the management information with respect to information held in another of the storage regions (31, 32). wherein the storage regions (31, 32) include: an information storage region (131, 132) for storing information, and a management information storage region (133, 134) for storing management information indicating a write state of information to the storage regions (31, 32), an information storage region (131, 132) for storing information, and a management information storage region (133, 134) for storing management information indicating a write state of information to the storage regions (31, 32), wherein the electronic control device is adapted so that: during a driving cycle, the management information storage region (133, 134) holds a start mark (133A, 134A) indicating a write start of the information, and during self-shutdown, the management information storage region (133, 134) holds a completion mark (133B, 134B) indicating a write completion of the information, and during a driving cycle, the management information storage region (133, 134) holds a start mark (133A, 134A) indicating a write start of the information, and during self-shutdown, the management information storage region (133, 134) holds a completion mark (133B, 134B) indicating a write completion of the information, and wherein the nonvolatile memory includes, separately from the storage regions (31, 32), a management information access flag storage region for storing access information indicating if there has been an access to the management information, wherein the electronic control device is adapted so that: during the driving cycle, the management information access flag storage region holds a start mark access flag indicating if there has been an access to a registration address of the start mark (133A, 134A), and during self-shutdown, the management information access flag storage region holds a completion mark access flag indicating if there has been an access to a registration address of the completion mark (133B, 134B), during the driving cycle, the management information access flag storage region holds a start mark access flag indicating if there has been an access to a registration address of the start mark (133A, 134A), and during self-shutdown, the management information access flag storage region holds a completion mark access flag indicating if there has been an access to a registration address of the completion mark (133B, 134B), wherein the electronic control device is adapted so that record patterns of the management information storage region (133, 134) and the management information access flag storage region in a case where a battery disconnection abnormality has occurred are different from record patterns of the management information storage region (133, 134) and the management information access flag storage region in a case where a battery disconnection abnormality has not occurred, and the storage region (31, 32) stores the management information with respect to information held in another of the storage regions (31, 32).