Provided is a method and apparatus for avoiding a collision of a preamble in a base station. When a new base station is installed in a mobile communication system and in this instance, an exclusive preamble using a contention-free scheme is employed to avoid a preamble collision, at least one of a code parameter, a time parameter, and a frequency parameter used in a preamble of the new base station may be set to be different from a code parameter, a time parameter, and a frequency parameter used in a preamble of a neighboring cell, whereby it is possible to manage a random access preamble without causing a collision between cells.