To provide an OFDM communication system and an OFDM communication method by which deterioration in an error rate characteristic of a demodulation signal can be prevented.

A counter 507 counts signals denoting that an integration result exceeds a 1st threshold value. A magnitude correlation comparison section 508 controls a switch 501 to be closed when the count of the counter 507 reaches the unity or over. A discrimination section 503 controls a switch 504 so that the result of integration is outputted to a subtractor 505 when the result of integration is once a 2nd threshold value or below. A discrimination 506 outputs information to reset the 1st threshold value when the result of integration is in excess of a 3rd threshold value on the basis of the result of subtraction by the subtractor 505.