A station-building power supply device is provided in each station building and supplies low-voltage AC power to station building facilities of each station building. There are two mode therein: a regenerative mode in which, when regenerative power regenerated by a train to an overhead wire becomes surplus, the surplus regenerative power supplied from the overhead wire and power supplied from a high-voltage distribution line are used together to supply low-voltage AC power corresponding to an amount of normal power consumption of the station building; and a standby power supply mode in which, when a power outage of the high-voltage distribution line occurs, power supplied from the overhead wire is used to supply low-voltage AC power corresponding to an amount of emergency power of the station building.