ARITHMETIC PROCESSING DEVICE, VEHICLE CONTROL DEVICE, AND UPDATE METHOD

When a control program is updated by a device that can select and execute one of two control programs, an amount of data to be transferred is reduced to shorten time required for update of a program. A first rewritable storage unit that stores two programs, a CPU that selects and executes one of the two programs, and a second rewritable storage unit that stores common data accompanying the two programs are included.