The present invention relates to an access control method and device in a wireless power transmission system. A wireless power transmission device comprises: a power conversion circuit configured to have a plurality of primary coils and transmit wireless power to a wireless power reception device by using the primary coil which has formed magnetic coupling to the wireless power reception device at an operating frequency; and a communication/control circuit configured to perform in-band communication with the wireless power reception device by using the operating frequency and perform out-band communication with the wireless power reception device by using a frequency other than the operating frequency, wherein the communication/control circuit can transmit information for notifying whether or not connection to the wireless power reception device is possible by using the out-band communication.