A method of determining vulnerability of web application comprises: selecting fixed parameters from parameters of URL link extracted from a website; determining whether a process of determining vulnerability for the selected fixed parameter is completed or not; inserting an attack pattern for each attack type to an input value for the selected fixed parameter, when the process of determining vulnerability for the selected fixed parameter is not completed; and determining vulnerability of the selected fixed parameter by each attack type through an analysis of response to an input of URL link with the attack pattern inserted thereinto.