SOFTWARE UPDATE DEVICE, UPDATE CONTROL METHOD, AND NON-TRANSITORY STORAGE MEDIUM

A software update device is configured to control software update of an electronic control unit mounted on a vehicle. The software update device includes: one or more storage devices configured to store first software and second software for downloading update data of the electronic control unit from a server, the first software and the second software being different from each other; and one or more processors configured to download the update data from the server by executing any of the first software and the second software.