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

A software update device (11) is configured to control software update of an electronic control unit (13a, 13b, 13c, 13d) mounted on a vehicle. The software update device (11) includes: one or more storage devices (34) configured to store first software and second software for downloading update data of the electronic control unit (13a, 13b, 13c, 13d) from a server (1), the first software and the second software being different from each other; and one or more processors (31) configured to download the update data from the server (1) by executing any of the first software and the second software.