A power-saving network management server, which is coupled to a network system including a network device and manages a state of power to the network device, wherein the power-saving network management server is configured to: store network configuration information and task allocation information; determine starting or stopping of the power supply to the port of the network device based on the updated network configuration information and task allocation information; store a determination result of the starting or stopping of the power supply to the port as a port determination result; and control the power supply to the port of the network device based on the port determination result.