A power supplying device for supplying power through a network to a plurality of communication terminals to transmit or receive data in a form of a packet including: a power supply controlling unit to preset a count of the communication terminals which are to be targeted for power supply, for every predetermined time period, out of the plurality of communication terminals, and to measure a flow rate of packets to be transmitted or received for every communication terminal to which power is being supplied, out of the communication terminals targeted for the power supply in each time period, and to supply power to at least one communication terminal to which power is not yet being supplied, out of the communication terminals targeted for the power supply, when the measured flow rate of packets in any communication terminal becomes not less than a predetermined threshold.