This invention relates to a word synchronization system which receives signals with error correction codes to calculate a syndrome from an initial phase, changes the initial phase when the calculated syndrome is not zero to calculate it anew, and repeats the operation until the time when the particular syndrome becomes zero for the sequence of M time (or the number of testing stages). This invention system is further provided with a synchronization slip detecting circuit to judge such a slip out of the synchronization without the necessity to wait for the repetition of the state for M times to thereby enable prompt phase resetting or synchronization establishment. -
WORD SYNCHRONIZATION SYSTEM