Disclosed is a scenario generation program that is used to generate a scenario given to a plurality of virtual web clients each of which applies access load to a web server device of a test target. According to the program, a computer stores some first request messages transmitted to a web server device and some second request messages transmitted to the web server device based on the same operation. The computer extracts the differences between the request parameters in the first and second request messages in the same order of the same operation. If page data of a response message includes the extracted request parameters, rewriting-item information is generated corresponding to the request parameter and is incorporated into the scenario. The computer replace the parameter shown by the rewriting-item information whenever the computer executes the scenario.