An electric power system includes a vehicle, a vehicle management server, an AC charging stand, a DC charging stand, and a charging stand management server. During AC charging and AC discharging, the AC charging stand is connected to the vehicle. An amount of charging power during AC charging and an amount of discharging power during AC discharging are calculated by the vehicle. The vehicle measures electric power before power conversion by an on-board charger, and calculates an amount of charging power and an amount of discharging power. An amount of charging power during DC charging and an amount of discharging power during DC discharging are calculated by the DC charging stand. The DC charging stand measures electric power before power conversion by a charger, and calculates an amount of charging power and an amount of discharging power.