An uninterruptible power supply includes an AC input terminal (T1) to receive AC power from a commercial AC power source (11), a battery terminal (T2) connected to a battery (12), first and second AC output terminals (T3, T4) connected to first and second loads (13, 14), respectively, a first uninterruptible power source (1-3) to supply AC power to the first load (13) on a full-time inverter feeding system, and a second uninterruptible power source (4-6) to supply AC power to the second load (14) on a full-time commercial feeding system.