An uninterruptible power supply system comprising N (N being an integer not less than two) uninterruptible power supply apparatuses (U1 to U3) connected in parallel, each uninterruptible power supply apparatus including: first and second input terminals (T4, T5) each configured to receive first AC power from a commercial AC power supply; an output terminal connected to a load; a first switch connected between said first input terminal and said output terminal; a converter configured to convert said first AC power supplied from said commercial AC power supply via said second input terminal into DC power; an inverter configured to convert said DC power into second AC power; a chopper configured to supply DC power from said converter to a power storage device when said first AC power is supplied and configured to supply DC power from said power storage device to said inverter when supply of said first AC power is stopped; a second switch connected between an output node of said inverter and said output terminal; an operation unit for selecting any power feeding mode from a first power feeding mode in which said first AC power is supplied to said load and a second power feeding mode in which said second AC power is supplied to said load; and a control unit configured to control said first and second switches (S1, S2) based on a selection result of said operation unit, N said control units of said N uninterruptible power supply apparatuses (U1 to U3) being coupled to each other via a communication line (C1, C2) to form one total control unit, said operation unit configured to select any power feeding mode from said first power feeding mode and said second power feeding mode in response to a touch on said operation unit, said total control unit configured to bring all of N said first switches of said N uninterruptible power supply apparatuses (U1 to U3) into conduction when said first power feeding mode is selected by any one said operation unit of N said operation units of said N uninterruptible power supply apparatuses (U1 to U3) and configured to bring all of N said second switches of said N uninterruptible power supply apparatuses (U1 to U3) into conduction when said second power feeding mode is selected by any one said operation unit of N said operation units, said communication line including (N-1) sets of M (M being a natural number) communication cables (C1, C2) provided respectively at (N-1) locations between said N control units or said communication line including N sets of M (M being a natural number) communication cables (C1 to C3) connecting said N control units in a loop, and each two of said control units being connected to each other by the M communication cables (C1, C2; C1, C2 or C3). first and second input terminals (T4, T5) each configured to receive first AC power from a commercial AC power supply; an output terminal connected to a load; a first switch connected between said first input terminal and said output terminal; a converter configured to convert said first AC power supplied from said commercial AC power supply via said second input terminal into DC power; an inverter configured to convert said DC power into second AC power; a chopper configured to supply DC power from said converter to a power storage device when said first AC power is supplied and configured to supply DC power from said power storage device to said inverter when supply of said first AC power is stopped; a second switch connected between an output node of said inverter and said output terminal; an operation unit for selecting any power feeding mode from a first power feeding mode in which said first AC power is supplied to said load and a second power feeding mode in which said second AC power is supplied to said load; and a control unit configured to control said first and second switches (S1, S2) based on a selection result of said operation unit, N said control units of said N uninterruptible power supply apparatuses (U1 to U3) being coupled to each other via a communication line (C1, C2) to form one total control unit, said operation unit configured to select any power feeding mode from said first power feeding mode and said second power feeding mode in response to a touch on said operation unit, said total control unit configured to bring all of N said first switches of said N uninterruptible power supply apparatuses (U1 to U3) into conduction when said first power feeding mode is selected by any one said operation unit of N said operation units of said N uninterruptible power supply apparatuses (U1 to U3) and configured to bring all of N said second switches of said N uninterruptible power supply apparatuses (U1 to U3) into conduction when said second power feeding mode is selected by any one said operation unit of N said operation units, said communication line including (N-1) sets of M (M being a natural number) communication cables (C1, C2) provided respectively at (N-1) locations between said N control units or said communication line including N sets of M (M being a natural number) communication cables (C1 to C3) connecting said N control units in a loop, and each two of said control units being connected to each other by the M communication cables (C1, C2; C1, C2 or C3).