In a wireless telecommunication system, a power control apparatus performs a data telecommunication with a control target apparatus and receives data arrival acknowledgement information transmitted therefrom in a data retransmission layer. Then it judges a reception quality of the control target apparatus by using the received data arrival acknowledgement information and changes a target power quality which is set up for the control target apparatus based on a result of the judgment. And it notifies the control target apparatus of the changed target power quality.