A transmission power control system can establish synchronization by matching adjustment start timings while repeating adjustment periods even when start timings of transmission power balance adjustment are different due to fluctuation of transmission delay of control message from the control station to base station, and can increase circuit capacity by establishing balance of transmission powers between the base stations. In the transmission power control system the base station comprises control means for controlling initiation of a balance adjustment period for performing the balance adjustment from a frame number determined on the basis of frame number of the balance adjustment period.