The purpose of this paper is to report the details of the network monitoring system with the SNMP (Simple Network Management Protocol), which was experimentally introduced to Kochi Gakuen College LAN. The results of the packet flow measurement carried out by this system are also reported. The results of the comparison of inputs and outputs of packet flow with SNMP indicate that inputs of WAN and outputs to 1st, 2nd, 3rd buildings are almost the same, which suggests that most of Kochi Gakuen College LAN users are in these buildings. It turns out from the results that SNMP is a useful protocol in order to cope with network troubles promptly, and to save labors for the pinpointing the exact location of network troubles.