A network management system which allows handling of data having a large data size without making changes to a management apparatus. In the system, the prefix is set to a value for identifying a table object containing image data, and the suffix is set to "0" (S110). A piece of data specified by the prefix and the suffix is obtained using a GET_NEXT command. If the prefix indicated by the received GETREPLY is identical with the prefix specified by the transmitted GET_NEXT command, the received data is added to image data being formed in a data combining portion. Then, the suffix indicated by the GETREPLY is set as the suffix of the GET_NEXT command to be transmitted next, and the same operation is repeatedly performed. On the other hand, if the two prefixes are different, the received data is discarded and the present process is terminated (S120-S160).