An uninterruptible power supply system includes a plurality of uninterruptible power supply devices, and each uninterruptible power supply device includes a conversion circuit, an inversion circuit, a DC positive bus, a DC negative bus, and a capacitor. The uninterruptible power supply system includes a first fuse connected between DC positive buses of two uninterruptible power supply devices, and a second fuse connected between DC negative buses of the two uninterruptible power supply devices. DC voltages between the plurality of DC positive buses and between the plurality of DC negative buses can be made uniform and a cross current can be suppressed. Even when one uninterruptible power supply device fails and an overcurrent flows between the two DC positive buses and between the two DC negative buses, the failure range can be narrowly limited by the first and second fuses.