PURPOSE: To enable to enlarge the limit of correction for error data by making the data decided as an uncorrected error wait for a stated time and anticipating the pointer information in the successive data group.

CONSTITUTION: By logical operation results 21 and 22 of syndrome generating circuits S1 and S2 and error position indicating information of pointer circuit 2, error decision circuit 4 decides wether an error occurs in the data group or not and the error can be corrected or not; if there is no error, data stored in buffer 3 is transferred to circuit 4. When existence of errors is confirmed and the error can be corrected by syndromes 21 and 22 and pointer 2 information, the error patturn of the position to be corrected is generated 7 and contents of buffer 3 are corrected by correction circuit 5. When data is decided as uncorrected one, a correction unable signal is sent to wait control circuit 6 through signal line 8, correcting operation is stopped for a stated time and circuit 4 is reset; referring to the pointer, the data are returned to the sequence which can decide errors.