A battery system includes first to N-th battery modules sequentially connected in a daisy chain configuration; and a master controller connected to the first battery module through an interface IC, selecting at least one target module among the first to N-th battery modules, and transmitting a control command for the target module. The target module unidirectionally transmits the control command received from the master controller, and bidirectionally transmits response data generated in response to the control command. The master controller selects the N-th battery module as the target module first, and selects the first battery module as the target module last.