Disclosed herein is a wireless power transmitting device that includes a charging module which is configured to transmit a foreign object sensing signal for sensing at least one of a wireless power receiving device and a foreign object on a charging pad, and which is configured to transmit a wireless power signal for charging the wireless power receiving device, and a control module which is configured to control the charging module such that the wireless power signal and the foreign object sensing signal are transmitted, and which is configured to sense at least one of the foreign object and the wireless power receiving device, based on an output voltage sensed by the charging module, after the foreign object sensing signal is transmitted.