A frequency synchronization apparatus includes: a correlating unit that obtains a first correlation value by correlating a known reference guard interval of an OFDM symbol and a reference copy interval corresponding to the reference guard interval, and obtains a second correlation value by correlating the estimate guard interval and an estimate copy interval corresponding to the estimate guard interval; a determining unit that compares the first and second correlation values to determine a first case where the first correlation value is larger by a pre-set magnification than the second correlation value, a second case where the second correlation value is larger by a pre-set magnification than the first correlation value, and a third case which is not the first case nor the second case; and a frequency offset estimating unit that estimates a frequency offset by using a correlation value corresponding to any one of the first to third.