A recorder to write content data on a storage medium and includes: a determining section, which receives incoming content data and determines data properties thereof; a selecting section for selecting, depending on whether a predetermined condition is satisfied, either a first type of write processing to add the data to an existent file on the storage medium or a second type of write processing to write the data as a new file; and a writing section for writing the data on the storage medium by performing the selected type of write processing. The selecting section selects the first type of write processing if at least one part of the data properties of the data that have been determined by the determining section is identical with those of the data that is stored in the existent file on the storage medium but selects the second type of write processing unless this condition is satisfied.