Abstract: Pointer renewal apparatus for AU-4 and TU-3 at an NNI of SDH recommended by CCITT, G707-G709. The apparatus comprises a retiming block 1 for input data, a pointer-detecting block 2 for the TU-3 pointer from input data, a pointer-analyzing block 4, a main memory block 6 for storing input data in a block frame of STM-1/3, a new pointer-generating block 8 which combines the AU-4 pointer and TU-3 pointer received into a new TU-3 pointer, a pointer-changing and output data block 7, and blocks which supply necessary pulses and signals such as extracting pulses for extracting the TU-3 pointer from the input data-block 3, generating frame-head signal pulses for the stored data-block 5, output timing pulses for the AU-4 pointer and TU-3 pointer-block 9, pulses and alarm signals indicating loss of a pointer and alarm indication signals AIS, and a read/write error-block 10.