An apparatus for reproducing data, method thereof and recording medium are disclosed. In reproducing a title configured with data within a recording medium and/or data within a local storage, a method of reproducing data, the present invention includes the steps of checking information of identifying an application associated with the title from an object file corresponding to the title, authenticating the associated application, and reproducing the title by executing the application. Accordingly, the present invention can protect contents provided by a content provider and a user's playback system. Hence, the content provider can provide contents safely and the user can reproduce the contents with security. Therefore, the present invention can provide more convenient functions.