To avoid adverse effect on coded data by absorbing interval fluctuations of synchronizing and converting the signal into a digital image signal without disturbance in the case that the synchronizing interval of the received digital image signal is disturbed.

A received digital image signal is stored in a frame memory 2 and read according to a read address from a read address generator 5. The read address generator 5 is controlled by an output of a synchronizing signal generator 6. Since the synchronizing signal generator 6, a voltage controlled oscillator 7, a low-pass filter 8 and a phase comparator 9 configure a phase locked loop, even when a digital image signal whose synchronizing interval is disturbed is received and the synchronizing interval extracted by the synchronizing signal detector 3 is disturbed, the synchronizing signal generated from the synchronizing signal generator 6 follows the interval fluctuation slowly. As a result, no disturbance is in existence in the digital signal read from the frame memory 2.