A device for controlling an assembled battery provided with a plurality of single batteries (C1, C2,..., CN), the device comprising: a targeted voltage setting means configured for setting a targeted voltage (V tar) to equalize voltages of the plurality of single batteries (C1, C2,..., CN) constructing the assembled battery; a capacity adjustment means (504, 505) configured for adjusting a capacity such that the voltages of the plurality of single batteries (C1, C2,..., CN) constructing the assembled battery are equalized at the targeted voltage (V tar); an internal state detection means configured for detecting terminal voltages or SOC of the plurality of single batteries (C1, C2,..., CN) and for calculating, based on the detected terminal voltages or the detected SOC, a voltage difference (ΔV) or a SOC difference among the plurality of single batteries (C1, C2,..., CN) as voltage-difference data or SOC-difference data, said difference being defined as the difference between the highest voltage or SOC and the lowest voltage or SOC; and a time-series data storage means configured for storing the voltage-difference data or the SOC-difference data, detected by the internal state detection means, in time-series, characterized in that the device further comprises: a SOC-voltage table storage means configured for storing a table showing a relationship between the SOC and the terminal voltage of each of the plurality of single batteries (C1, C2,..., CN), and a prediction means configured for predicting the time when a first abnormal state of the assembled battery is predicted to occur, based on (a) a time-dependent change in the voltage-difference data detected in a voltage region different from the targeted voltage (V tar) by a predetermined voltage (V 1) or more, or (b) a time-dependent change in the SOC-difference data detected in a SOC region corresponding to the voltage region different from the targeted voltage (V tar) by the predetermined voltage (V 1) or more, among the voltage-difference data or the SOC-difference data stored in the time-series data storage means. a targeted voltage setting means configured for setting a targeted voltage (V tar) to equalize voltages of the plurality of single batteries (C1, C2,..., CN) constructing the assembled battery; a capacity adjustment means (504, 505) configured for adjusting a capacity such that the voltages of the plurality of single batteries (C1, C2,..., CN) constructing the assembled battery are equalized at the targeted voltage (V tar); an internal state detection means configured for detecting terminal voltages or SOC of the plurality of single batteries (C1, C2,..., CN) and for calculating, based on the detected terminal voltages or the detected SOC, a voltage difference (ΔV) or a SOC difference among the plurality of single batteries (C1, C2,..., CN) as voltage-difference data or SOC-difference data, said difference being defined as the difference between the highest voltage or SOC and the lowest voltage or SOC; and a time-series data storage means configured for storing the voltage-difference data or the SOC-difference data, detected by the internal state detection means, in time-series, characterized in that the device further comprises: a SOC-voltage table storage means configured for storing a table showing a relationship between the SOC and the terminal voltage of each of the plurality of single batteries (C1, C2,..., CN), and a prediction means configured for predicting the time when a first abnormal state of the assembled battery is predicted to occur, based on (a) a time-dependent change in the voltage-difference data detected in a voltage region different from the targeted voltage (V tar) by a predetermined voltage (V 1) or more, or (b) a time-dependent change in the SOC-difference data detected in a SOC region corresponding to the voltage region different from the targeted voltage (V tar) by the predetermined voltage (V 1) or more, among the voltage-difference data or the SOC-difference data stored in the time-series data storage means. a SOC-voltage table storage means configured for storing a table showing a relationship between the SOC and the terminal voltage of each of the plurality of single batteries (C1, C2,..., CN), and a prediction means configured for predicting the time when a first abnormal state of the assembled battery is predicted to occur, based on (a) a time-dependent change in the voltage-difference data detected in a voltage region different from the targeted voltage (V tar) by a predetermined voltage (V 1) or more, or (b) a time-dependent change in the SOC-difference data detected in a SOC region corresponding to the voltage region different from the targeted voltage (V tar) by the predetermined voltage (V 1) or more, among the voltage-difference data or the SOC-difference data stored in the time-series data storage means.