Electronic Control Device and Program-Update Method

A program-update method for an electronic control device including a nonvolatile memory having allocated two storage areas that are exclusively switchable between an active state and an inactive state, the two storage areas being set such that in a state in which a program is written in the storage area in the active state, a program is written for updating to the storage area in the inactive state in response to an instruction from an external device, followed by switching the storage area in the active state to the inactive state and switching the storage area in the inactive state to the active state,

• the program-update method comprising, when the program written in the storage area in the active state differs from the program written in the storage area in the inactive state, copying, by the electronic control device, the program written in the storage area switched to the active state to the storage area in the inactive state.