A method and an apparatus, in a mobile communication system, for effectively providing configuration information about a small cell that has a small cell service region are provided. The method for transmitting reconfiguration information of a small cell base station in a mobile communication system includes: when deciding to reconfigure a small cell, obtaining the latest macro cell configuration information from a macro cell base station; generating reconfiguration information about the small cell on the basis of the obtained macro cell configuration information; and transmitting, to the macro cell base station, the regenerated reconfiguration information so that the macro cell base station can transmit the reconfiguration information to User Equipment (UE).