We propose a management system for wireless sensor networks based on Simple Network Management Protocol (SNMP). SNMP is the standard network management protocol that facilitates the exchange of management information between network devices to monitor managed devices, and is widely deployed and available in almost all network devices. Using SNMP to manage WSNs, we can get an integrated management view of multiple WSNs that have heterogeneous systems and protocols. Because a sensor node is incapable of running an SNMP agent due to lack of resources, we propose an approach that uses the base station as an SNMP agent representing other sensor nodes.