A device for transmission of wireless power according to an embodiment of the present specification comprises: a power conversion circuit for transmitting the wireless power to a wireless power receiving device; and a communication/control circuit for communicating with the wireless power receiving device and controlling the wireless power, wherein the communication/control circuit transmits a response to a reception data packet received from the wireless power receiving device or a transmission data packet transmitted to the wireless power receiving device on the basis of a timeout period, and the timeout period is changed according to a communication speed between the communication/control circuit and the wireless power receiving device.