A data processing apparatus is disclosed which includes a reproducing element for reproducing each of a plurality of content data items, a reproduction status detecting element for detecting status of each content data item being reproduced by the reproducing element, a selecting element for selecting the content data item being reproduced by the reproducing element depending on the reproduction status of the content data item detected by the reproduction status detecting element a content identification data generating element for generating content identification data for identifying the content data item selected by the selecting element from the plurality of content data items, and a transmitting element for transmitting to a second data processing apparatus the content identification data generated by the content identification data generating element.