A battery monitoring system includes a plurality of battery monitoring devices connected to a battery formed by connecting a plurality of battery cell groups in series, and monitor a state of the battery for the respective battery cell groups, each of the plurality of battery cell groups being of one or a plurality of battery cells connected in series, and a controller that performs wireless communication with the plurality of battery monitoring devices. First identification information portions which are different from each other are set in the plurality of battery monitoring devices in advance, and second identification information corresponding to an order of potentials of the battery cell groups in the battery, to which the battery monitoring devices are connected, is assigned to each of the plurality of battery monitoring devices. The controller stores a relationship between the first and second identification information for each battery monitoring device.