Power limiting apparatus for electric system, power limiting method for electric system and electric system

In a first condition, the sum of discharging power from a first battery stack (110) and discharging power from a second battery stack (120) is limited in accordance with the sum of a limit value (WOUT) of discharging power from the first battery stack and a limit value (WOUT) of discharging power from the second battery stack. In a second condition, electric power of the battery stacks is limited in accordance with either of limit value (WOUT) of discharging power from the first battery stack and limit value (WOUT) of discharging power from the second battery stack.