Disclosed is a configuration of a guard band for a radio communication system formed of consecutive sub-bands. Particularly disclosed are designs of a middle guard band for preventing interference between adjacent sub-bands and regulating a difference in frequency between signals transmitted in each sub-band in a radio communication system such as a multi-carrier OFDM system and a multi-carrier CDMA system that forms a wideband through carrier aggregation. Related transmission/reception method and apparatus are further disclosed.