Update device and update method

A storage unit (14) stores package management information (14a), which includes an association between a file and a package containing the file and information indicating whether there is a dependency relationship between a plurality of packages, and an ACL (14b), which includes an association between an access destination file and an access source file that is permitted to access the access destination file. When a combination of an access destination file and an access source file is specified, an identification unit (15a) references the package management information (14a) and identifies a package that includes the access destination file and a package that includes the access source file. When the identified package that includes the access destination file and the identified package that includes the access source file are the same or have a mutual dependency relationship, an addition unit (15b) adds the specified combination to the ACL (14b).