Disclosed are methods of exchanging messages necessary for interaction among entities in a coexistence management system that manages a plurality of frequency sharing devices. Specifically, a method of exchanging messages in a coexistence management system including a coexistence enabler (CE), a coexistence manager (CM), and a coexistence discovery and information server (CDIS) includes generating, by the CM, a ReconfigurationRequest message, sending the ReconfigurationRequest message to the CE, and waiting for a ReconfigurationResponse message from the CE. The ReconfigurationRequest message includes at least one of an operating channel list of a white space object (WSO) served by the CE, a transmission power limitation, a flag indicating whether or not a channel is shared, a transmission schedule, and channel classification information.