Provided is a web firewall for automatically checking for vulnerabilities, including: an administrating server scheduling part for ordering the examination of an administrating web server according to a predetermined examination schedule; a vulnerability search database calling part for calling a vulnerability search database previously stored according to the order of the administrating server scheduling part; a vulnerability searching part for searching for potential vulnerabilities of the administrating web server corresponding to data included in the called vulnerability search database; a vulnerability information deducing part for optimizing the results searched in the vulnerability searching part to deduce vulnerability information; a vulnerability checking part for checking the vulnerabilities of the administrating web server based on the results deduced from the vulnerability information deducing part; and a detailed vulnerability information reporting part for reporting detailed information on the checked vulnerabilities.