A method for transmitting a preamble in a scalable bandwidth system is disclosed. The method includes transmitting a primary synchronization channel to which symbols are allocated at intervals of two or more subcarriers, through a specific bandwidth out of an entire system bandwidth at a start time point of a synchronization period, and transmitting a secondary synchronization channel through the specific bandwidth with a prescribed time difference from the primary synchronization channel at the synchronization period. A mobile station can use the same search routine irrespective of a system bandwidth, does not experience any difficulty at a cell edge in establishing signal timing synchronization, can simply perform preamble search, and can transmit a signal in a maximum usable bandwidth, thereby improving the accuracy of location measurement.