A control method of a wireless power transmitting unit transmitting charging power to a wireless power receiving unit is provided. The control method includes receiving first signals from one or more wireless power receiving units; classifying wireless power receiving units to be communicated with from among the one or more wireless power receiving units based on reception intensities of the received first signals; transmitting wireless transmission power with predetermined level; receiving second signals including voltage information of the classified wireless power receiving units from the classified wireless power receiving units; and communicating with one or more wireless power receiving unit among the classified wireless power receiving units based on the wireless transmission power and the voltage information of the second signals.