A method for managing flow information of a mobile station by a handover target base station in a communication system, the method comprising: receiving a ranging request message, which includes a flow identifier for each of flows between a serving base station and the mobile station and a change count indicating the number of times of an addition/change/deletion operation of flow information of a corresponding flow for each of flow identifiers, from the mobile station; and transmitting a ranging response message, which includes a validity indicator indicating whether the change count of each of the flow identifiers is valid or not, to the mobile station, wherein, if the validity indicator indicates that at least one change count among change counts for each of the flow identifiers is not valid, the ranging response message comprises a list of flow identifiers including the flow identifier having the at least one change count that is not valid, wherein the transmitting of the ranging response message comprises: if change counts for each of the flow identifiers completely coincide with change counts stored in the target base station, configuring the validity indicator to indicate that all the change counts for each of the flow identifiers are valid; and if the change counts for each of the flow identifiers include at least one change count which does not coincide with any of the change counts stored in the target base station, configuring the validity indicator to indicate that the change counts for each of the flow identifiers include at least one invalid change count. receiving a ranging request message, which includes a flow identifier for each of flows between a serving base station and the mobile station and a change count indicating the number of times of an addition/change/deletion operation of flow information of a corresponding flow for each of flow identifiers, from the mobile station; and transmitting a ranging response message, which includes a validity indicator indicating whether the change count of each of the flow identifiers is valid or not, to the mobile station, wherein, if the validity indicator indicates that at least one change count among change counts for each of the flow identifiers is not valid, the ranging response message comprises a list of flow identifiers including the flow identifier having the at least one change count that is not valid, wherein the transmitting of the ranging response message comprises: if change counts for each of the flow identifiers completely coincide with change counts stored in the target base station, configuring the validity indicator to indicate that all the change counts for each of the flow identifiers are valid; and if the change counts for each of the flow identifiers include at least one change count which does not coincide with any of the change counts stored in the target base station, configuring the validity indicator to indicate that the change counts for each of the flow identifiers include at least one invalid change count. if change counts for each of the flow identifiers completely coincide with change counts stored in the target base station, configuring the validity indicator to indicate that all the change counts for each of the flow identifiers are valid; and if the change counts for each of the flow identifiers include at least one change count which does not coincide with any of the change counts stored in the target base station, configuring the validity indicator to indicate that the change counts for each of the flow identifiers include at least one invalid change count.