To provide a multilevel QAM demodulation method and apparatus for preventing erroneous decoding caused by erroneous demapping by monitoring a specific synchronizing word symbol.

In the multilevel QAM demodulation method, a decoded signal is obtained by receiving a multilevel QAM signal, synchronizing frames by using the synchronizing word symbol and a pilot symbol, creating a threshold for determination from the average value of the amplitude information of the pilot symbol and determining the received multilevel QAM signal on the basis of the threshold for determination. It is determined whether the specific symbol in the synchronizing word symbol is right or not and when the errors continue equal with or longer than the predetermined number of times, the frame synchronization is canceled, and the threshold for determination is calculated on the basis of the amplitude information of the single pilot symbol.