A method of determining a power transmission device to be set as a master device such that wasteful communication is not caused. In a wireless power feeding system, a power transmission device that transmits electric power to a power reception device forms a group with other power transmission devices. The power transmission device performs communication with the power reception device or the other power transmission devices using a wireless transmission section and a wireless reception section, and exchanges information with the other power transmission devices. The power transmission device receives a setting for determining a power transmission device to be set as a master device out of the self device and the other power transmission devices, with which information has been exchanged. If the received setting is for setting the self device as the master device, the self device is set as the master device.