1. An applicable patch selection device, comprising: an input device to input a user's policy; and a processing unit to extract first information on unapplied patches targeted to a package installed on an application target system from among information on released patches by comparing information on the installed package with information on packages fixed by the released patches, extract second information on unapplied patches in the application target system from among the extracted first information by comparing information on patches applied on the application target system with the extracted first information, extract third information on an unapplied patch which corresponds to a policy data input by the input device and is targeted to packages installed on the application target system from among the extracted second information by comparing information on a use frequency for the packages installed on the application target system with the policy data included information on a use frequency of package, and obtain an unapplied patch corresponding to the extracted third information.