Disclosed is a frame synchronizing apparatus in a receiving equipment for receiving digital signals for PCM communication. The digital signals consists serial signals at a rate of f.sub.0 (bps). The serial signals include a frame synchronizing signal consituting n bits or a part of the frame synchronizing signal, collectively arranged in one frame. To attain a high-speed operation and a shorter synchronization establishing time, the apparatus comprises a latching circuit for converting the serial signals into parallel signals and for latching the parallel signals, and a circuit for detecting a plural number of times of synchronization during the n bit interval in one frame.