A system for analyzing an information system connected between a plurality of information processors through a communication line, including: a capturing unit for capturing communication packets sent through the communication line; a first counting unit for extracting an attribute value representing communication attributes from each of the captured communication packets to add attribute values for each destination of the communication packets; a second counting unit for extracting an attribute value representing communication attributes from each of the captured communication packets to add attribute values for each source of the communication packets; and a determining unit for determining which of a server function and a client function uses a TCP/UDP port of each of the information processors on the basis of the total attribute value for communication packets addressed to the TCP/UDP port and the total attribute value for communication packets sent from the TCP/UDP port.