A line monitoring function unit collects message information and sequence information from an existing communication network. A data analyzing function unit converts the collected message information and sequence information into significant information defined for each communication protocol to analyze detailed information on the communication protocol. A scenario creating function unit creates/edits a test scenario and test message with the detailed information obtained by the data analyzing function unit. A data converting function unit converts the data from the scenario creating function unit. A test message input/output function unit executes a communication protocol test in accordance with a sequence of the test scenario obtained from the scenario creating function unit. A log buffer accumulates log information collected during the communication protocol test. An edit searching function unit accesses the scenario creating function unit to obtain a scenario of interest with a search keyword for edit of the information obtained at the scenario creating function unit.