An OTA master, the OTA master being configured to control software update for an electronic control unit (40a; 40b; 40c; 40d) mounted on a vehicle, the OTA master comprising: a communication unit configured to receive, from a center, a distribution package including: first update data for the electronic control unit on which a first-kind non-volatile memory having one storage area is mounted and second update data for the electronic control unit on which a second-kind non-volatile memory having two storage areas is mounted, and wherein the distribution package includes information of a memory type, characterized in that the OTA master is configured to: acquire the type of the non-volatile memory mounted on a target electronic control unit, ECU, by referring to the distribution package, the target ECU being an ECU of which software is to be updated, the target ECU having the first-kind non-volatile memory or the second-kind non-volatile memory, write (S1102, S1105) an update software on the storage area of the target ECU based on the update data and notify (S1102, S1105) the acquired type information to the target ECU, wherein the target ECU is configured to: determine (S1103, S1106) whether the type of the non-volatile memory mounted on the target ECU matches the memory type notified from the OTA master, and when the memory type notified from the OTA master does not match the type of the non-volatile memory mounted on the target ECU, notify (S1104, S1107) the OTA master that the memory type notified from the OTA master does not match the type of the non-volatile memory mounted on the target ECU. a communication unit configured to receive, from a center, a distribution package including: first update data for the electronic control unit on which a first-kind non-volatile memory having one storage area is mounted and second update data for the electronic control unit on which a second-kind non-volatile memory having two storage areas is mounted, and wherein the distribution package includes information of a memory type, characterized in that the OTA master is configured to: acquire the type of the non-volatile memory mounted on a target electronic control unit, ECU, by referring to the distribution package, the target ECU being an ECU of which software is to be updated, the target ECU having the first-kind non-volatile memory or the second-kind non-volatile memory, write (S1102, S1105) an update software on the storage area of the target ECU based on the update data and notify (S1102, S1105) the acquired type information to the target ECU, wherein the target ECU is configured to: determine (S1103, S1106) whether the type of the non-volatile memory mounted on the target ECU matches the memory type notified from the OTA master, and when the memory type notified from the OTA master does not match the type of the non-volatile memory mounted on the target ECU, notify (S1104, S1107) the OTA master that the memory type notified from the OTA master does not match the type of the non-volatile memory mounted on the target ECU. acquire the type of the non-volatile memory mounted on a target electronic control unit, ECU, by referring to the distribution package, the target ECU being an ECU of which software is to be updated, the target ECU having the first-kind non-volatile memory or the second-kind non-volatile memory, write (S1102, S1105) an update software on the storage area of the target ECU based on the update data and notify (S1102, S1105) the acquired type information to the target ECU, wherein the target ECU is configured to: determine (S1103, S1106) whether the type of the non-volatile memory mounted on the target ECU matches the memory type notified from the OTA master, and when the memory type notified from the OTA master does not match the type of the non-volatile memory mounted on the target ECU, notify (S1104, S1107) the OTA master that the memory type notified from the OTA master does not match the type of the non-volatile memory mounted on the target ECU. determine (S1103, S1106) whether the type of the non-volatile memory mounted on the target ECU matches the memory type notified from the OTA master, and when the memory type notified from the OTA master does not match the type of the non-volatile memory mounted on the target ECU, notify (S1104, S1107) the OTA master that the memory type notified from the OTA master does not match the type of the non-volatile memory mounted on the target ECU.