A transmitting apparatus is disclosed. The transmitting apparatus includes a preamble symbol inserter configured to insert to a frame a preamble symbol including a signaling information, a guard interval inserter configured to insert guard intervals to both ends of the preamble symbol, and a transmitter configured to transmit a frame including the preamble symbol and the guard intervals, wherein one of the guard intervals which are inserted to both ends of the preamble symbol comprises a pseudo random noise (PN) sequence and another guard interval includes one between the PN sequence and a part of the signaling information. Accordingly, no separate algorithm to estimate size of FFT of the preamble symbol and the guard interval is necessary, robust signal detection and synchronization is enabled by the PN sequence inserted to the guard interval, and compensation of interference which is generated under multipath channel environment deems to be easier.