A demodulator and a demodulating method for a WPAN are provided. In the demodulator for estimating a demodulation value of a received signal by correlating a PN code sequence of PN code having a periodic relationship for each code with a sample of the received signal, an IF processor unit separates the received signal to select only an imaginary part of the received signal, and digitalizes the selected imaginary part of the received signal. A differentiator unit delays the received signal outputted from the IF processor unit by preset delay time, and multiplies the delayed received signal by a current received signal to output a plurality of differentiated received signals. A conjugate unit sequentially stores samples of the imaginary parts of the differentiated received signals, and calculates correlation values by correcting the stored samples with PN coded sequences. A timing estimator unit receives the differentiated received signals and controls an operating timing of the conjugate unit. A demodulation value estimator unit stores the correlation values outputted from the conjugate unit and estimates the symbol of the PN code sequence corresponding to a maximum correlation value as the demodulation value of the received signal.