To provide a power source device for controlling a gas turbine for emergency capable of sharing a battery for starting or backing up a battery for control by a battery for starting, and capable of feeding only the power of the battery for control to a control system during operation of a starter.

This power source device is provided with the battery for starting to feed a power to the starter of the gas turbine and the battery for control to feed a power to a controller for the gas turbine. A circuit is provided to interconnect in parallel the battery for starting and the battery for control and the circuit is provided with a change-over switch to change over connection and disconnection between the battery for starting and the battery for control, and the battery for starting and the battery for control are cut off by opening a circuit by the change-over switch during operation of a starter. Further, when the battery for control is consumed, a power for the battery for control can be fed to the controller.