An active antenna system includes: a plurality of antennas; a plurality of switches respectively connected to the antennas, the switches being configured to switch between transmission signal lines and reception signal lines to perform Time Division Duplex; a plurality of transmitter-receivers respectively connected to the transmission signal lines and the reception signal lines; a calibration transmitter connected to the transmission signal lines; a calibration receiver connected to the reception signal lines; and a control unit configured to carry out, during a receiving time of the Time Division Duplex, reception calibration of each of the transmitter-receivers based on a signal transmitted by the calibration transmitter and received by the transmitter-receivers, and, during a transition time from reception to transmission, carry out transmission calibration of each of the transmitter-receivers based on a signal transmitted by the transmitter-receivers and received by the calibration receiver.