According to one embodiment, a method of driving a phased array antenna, includes applying voltages to phase control electrodes in a first period such that radio waves to be emitted from antennas are in a same phase in a first emission direction, and applying the voltages to the phase control electrodes in a second period such that the radio waves to be emitted from the antennas are held in the same phase in the first emission direction. An absolute value of the voltage applied in the second period is different from an absolute value of the voltage applied in the first period, in each of the phase control electrodes.