A frequency offset detector is provided which is adaptable to a great frequency offset of one or more carrier waves in an OFDM signal. The frequency offset detector comprises a multiplication circuit which multiplies, by a pseudorandom number bit sequence, a reception signal generated by Fourier transformation of an OFDM modulated signal wherein pilot symbols are dispersed and arranged in accordance with four kinds of patterns and periodically transmitted. Four arithmetic circuits extract the pilot symbols corresponding to the respective patterns from a result of the multiplication by the multiplication circuit for each of the four kinds of patterns and calculate the sum of phase differences among the extracted pilot symbols to output an absolute value. A detection circuit detects a frequency offset on the basis of a maximum value of the absolute values calculated by the four arithmetic circuits. A complex sinusoidal wave is generated on the basis of the detected frequency offset, and the frequency of an input signal is converted thereby, such that the offset of the reception signal can be corrected.