Disclosed is a method of estimating carrier frequency offset in an OFDM system. The method includes the steps of forming one OFDM symbol which has M repeated identical signal block, being a base sub-block; forming a 2i number of identical ith sub-blocks using an M/2i number of the M number of base sub-blocks as a unit; and estimating an ith carrier frequency offset &egr;i using a correlation between two adjacent ith sub-blocks in the 8i number of the ith sub-blocks.