an improved decoding apparatus for a manchester code receives an asynchronous manchester code , synchronizes to a received clock signal , and decodes an output nrz code and an output synchronous clock signal . a first decoding unit samples an asynchronous manchester code by synchronizing the asynchronous manchester code to a shift of a received clock signal to produce a synchronous manchester code and a synchronous clock , and computes an nrz code . a tolerance check unit receives the synchronous manchester code and checks a tolerance with respect to a shift at a bit cell center of the synchronous manchester code . a multiplexer unit receives the nrz code and the synchronous clock signal and selectively outputs a multiplexed nrz code and a multiplexed synchronous clock signal in accordance with a detection signal outputted from the tolerance check unit . a synchronous signal detection unit receives the multiplexed nrz code and the multiplexed synchronous clock signal and outputs a sync detection signal ; and a second decoding unit receives the multiplexed nrz code and the multiplexed synchronous clock signal and computes the output nrz data and the output synchronous clock signal in accordance with the sync detection signal .