In a blind detection apparatus and method capable of determining a modulation mode by comparing the absolute values of the real and imaginary parts of a sequence of intersymbol phase differences between symbols separated from each other at an interval of four symbols (instead of comparing intersymbol phase differences of symbols at an interval of one symbol as in the related art), the symbols being included in a training sequence code of a received normal burst. Therefore, a number of calculations for the blind detection may be decreased e.g., by a factor of four, and as a result, the time for performing the blind detection may be decreased. In addition, the hardware design for the blind detection may be simplified.