An updating system includes a plurality of electronic control units and an updating management device. The updating management device is configured to request that the electronic control units respectively update programs and store update results of the programs transmitted from the electronic control units. The electronic control unit has a first storage region and a second storage region, and is configured to store an updated program in the second storage region and notify the updating management device of the update results according to a request from the updating management device, and is configured to start a predetermined control using the updated program stored in the second storage region when the update results stored in the updating management device indicate that the updating of the programs in the electronic control units is completed.