1. A streaming distributing device comprising: a content fragment generating section configured to generate a fragment storing data of a content to be distributed by streaming, the fragment being defined by a Moving Picture Experts Group-4 Part 14 file format; and a subtitle fragment generating section configured to generate a fragment storing a Timed text markup language document instance relating to a subtitle to be displayed in said content, the fragment being defined by the Moving Picture Experts Group-4 Part 14 file format, wherein said subtitle fragment generating section adds, to header information of said fragment, instance classification distinguishing information for distinguishing whether said timed text markup language document instance stored in said fragment is a timed text markup language document instance specifying a rendering context relating to said subtitle.