A battery apparatus, comprising: plural battery modules connected in series each having plural battery cells (VB1,..., VB12) connected in series; plural low order control devices (IC-1, IC-2, IC-3) which are provided in correspondence with the plural battery modules, respectively, each of the plural low order control devices controlling the plural battery cells (VB1,..., VB12) configuring corresponding one of the plural battery modules and which have at least one input terminal (In) for inputting a command issued by a high order control device and at least one output terminal (Out) for outputting a command issued by the high order control device; and the high order control device which controls the plural low order control devices (IC-1, IC-2, IC-3); wherein each of said at least one input terminals (In) of the low order control device (IC-1) at the highest potential is connected to the high order control device through a respective isolating or potential converting unit (F1-F3); each of said at least one output terminals (Out) of the low order control device (IC-3) at the lowest potential is connected to the high order control device through a respective isolating or potential converting unit (F4-F6); and each of said input and output terminals (In, Out) are connected in an electrically non-isolated state among the plural low order control devices (IC-1, IC-2, IC-3), wherein each of the output terminals (Out) of the low order control devices at the highest potential and intermediate potentials are directly connected with respective input terminals of low order control devices directly following the low order control device at the previous potential, the battery apparatus further comprising interruption elements provided for each of said output terminals of the low order control devices, each of which interruption elements is disposed between the corresponding output terminal (Out) of one of the plural low order control devices and a battery cell in the battery module on a lower potential side of said low order control device and blocks discharge current of battery cells in said battery module. plural battery modules connected in series each having plural battery cells (VB1,..., VB12) connected in series; plural low order control devices (IC-1, IC-2, IC-3) which are provided in correspondence with the plural battery modules, respectively, each of the plural low order control devices controlling the plural battery cells (VB1,..., VB12) configuring corresponding one of the plural battery modules and which have at least one input terminal (In) for inputting a command issued by a high order control device and at least one output terminal (Out) for outputting a command issued by the high order control device; and the high order control device which controls the plural low order control devices (IC-1, IC-2, IC-3); wherein each of said at least one input terminals (In) of the low order control device (IC-1) at the highest potential is connected to the high order control device through a respective isolating or potential converting unit (F1-F3); each of said at least one output terminals (Out) of the low order control device (IC-3) at the lowest potential is connected to the high order control device through a respective isolating or potential converting unit (F4-F6); and each of said input and output terminals (In, Out) are connected in an electrically non-isolated state among the plural low order control devices (IC-1, IC-2, IC-3), wherein each of the output terminals (Out) of the low order control devices at the highest potential and intermediate potentials are directly connected with respective input terminals of low order control devices directly following the low order control device at the previous potential, the battery apparatus further comprising interruption elements provided for each of said output terminals of the low order control devices, each of which interruption elements is disposed between the corresponding output terminal (Out) of one of the plural low order control devices and a battery cell in the battery module on a lower potential side of said low order control device and blocks discharge current of battery cells in said battery module.