Provided is a software updating device for executing processing for updating software causing an equipment mounted on a vehicle to operate. The software updating device includes a controller that acquires the software, and controls the equipment by applying the software to the equipment. The controller includes a first storage unit that stores acquired first software and a second storage unit that stores acquired second software. In a state where no driving force is output by a power train of the vehicle, the controller executes processing for updating the software by changing software to be applied to the equipment from the first software to the second software.