The method for transmitting power wirelessly according to an embodiment may comprise checking a position of a receiving device while wirelessly transmitting power to the receiving device, and changing a charging stop level which is compared with power loss which corresponds to a difference between transmitted power transmitted to the receiving device and received power received by the receiving device when the receiving device is outside a charging area. The receiving device is outside the charging area may be determined based on that the received power is equal to or greater than reference power and a power control level when transmitting the power to the receiving device is equal to or greater than a reference value. The charging stop level may be returned to an original value when the power loss is lower than the changed charging stop level until a predetermined time elapses after changing the charging stop level.