The invention provides an electronic camera system which operates an electronic camera in a minimum power mode when a not-genuine secondary battery is attached to the electronic camera. Namely, for the electronic camera which uses a detachable secondary battery as a power source, it determines from identification information whether the secondary battery is a genuine battery of the electronic camera. When determining that the secondary battery is a genuine battery, the electronic camera system allows the electronic camera to normally operate. When determining that the secondary battery is not a genuine battery, it places the electronic camera into the minimum power mode.