The GOOSE(Generic Object Oriented Substation Event) is used as a network protocol to communicate between IEDs(Intelligent Electronic Devices) in international standard IEC 61850 of substation automation system. Nevertheless, the GOOSE protocol is facing many similar threats used in TCP/IP protocol due to ethernet-based operation. In this paper, we develop a IDS(Intrusion Detection System) for secure GOOSE Protocol using open software-based IDS Snort. In this IDS, two security functions for keyword search and DoS attack detection are implemented through improvement of decoding and preprocessing component modules. And we also implement the GOOSE IDS and verify its accuracy using GOOSE packet generation and communication experiment.